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Pagina personale di Franco GHELFI

Dipartimento di Scienze Chimiche e Geologiche
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

F. GHELFI; L. COTARCA; F. RONCAGLIA; R. GIOVANNETTI; A. NICOLI ( ) - PROCESS FOR PREPARING GABAPENTIN [Brevetto (285) - Brevetto]
Abstract

A process for preparing gabapentin of formula 1, which comprises Formula (I) converting 1-allyl-cyclohexanecarboxaldehyde into 1-allyl-cyclohexanecarbonitrile; ozonizing 1-allyl-cyclohexanecarbonitrile to obtain 1-cyano-cyclohexaneacetaldehyde; acetalizing 1-cyano-cyclohexaneacetaldehyde with a suitable acetalizing agent to give the corresponding acetal and converting the latter into gabapentin.

Clark, Andrew J; Curran, Dennis P.; Fox, David J.; Ghelfi, Franco; Guy, Collette S.; Hay, Benjamin; James, Natalie; Phillips, Jessica M.; Roncaglia, Fabrizio; Sellars, Philip B.; Wilson, Paul; Zhang, Hanmo ( 2016 ) - Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and Implications for their Cyclization Reactions - JOURNAL OF ORGANIC CHEMISTRY - n. volume 81 - pp. da 5547 a 5565 ISSN: 0022-3263 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG∞ rotation varied between <8.0 and 31.0 kcal mol-1). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG∞ rotation >20 kcal mol-1) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol-1) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical-polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.

Geden, Joanna V.; Clark, Andrew J.; Coles, Stuart R.; Guy, Collette S.; Ghelfi, Franco; Thom, Stephen ( 2016 ) - Copper mediated cyclization of 1-substituted enamides, dienamides and trienamides: regiochemistry, indigoid formation and methyl migration-aromatization - TETRAHEDRON LETTERS - n. volume 57 - pp. da 3109 a 3112 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Copper mediated cyclization of activated 1-substituted enamides occurs via a 5-endo radical-polar cross-over process. Trichloroacetyl derivatives can undergo further reactions post cyclization (elimination of HCl or dimerization potentially via copper carbenoid intermediates). Reaction of alpha-halo trienamides derived from beta-ionone furnish either beta- or gamma-lactams via 4-exo or 5-exo cyclizations respectively depend- ing upon the enamide tautomer undergoing reaction. For the less reactive dichloroacetamide derivative a competing regioselective methyl migration-aromatization prior to cyclization is observed.

Isse, Abdirisak A.; Ghelfi, Franco; Roncaglia, Fabrizio; Gennaro, Armando; Visona, Giulia ( 2015 ) - Electrochemical Approach to Copper-Catalyzed Reversed Atom Transfer Radical Cyclization - ADVANCED SYNTHESIS & CATALYSIS - n. volume 357 - pp. da 782 a 792 ISSN: 1615-4150 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Electrochemically mediated atom transfer radical cyclization (eATRC) has been developed as an easy and clean method allowing the synthesis of halogenated cyclic compounds. This method has been successfully applied to the copper-catalyzed atom transfer radical cyclization of some N-allyl-alpha,alpha-dichloroamides in acetonitrile (CH3CN) using a copper complex with tris(2-pyridylmethyl)amine (TPMA) with a metal loading of 1%. The catalyst is introduced as [Cu(II)TPMA](2+) and is activated and continuously regenerated to its active copper(I) form by reduction at a platinum (Pt) electrode. During the ATRC process a new copper(II) complex, namely, [ClCu(II)TPMA](+), whose reduction potential is ca. 0.350 V more negative than that of the starting [Cu(II)TPMA](2+), is formed. Therefore, the choice of the applied potential is critical and should be done taking care that all copper(II) species are reduced to copper(I). The compounds undergo very high conversions (79-100%) in a few hours of electrolysis, producing a cyclic gamma-lactam (yield 60-98%) as a mixture of two isomers, with a good cis-diastereoselectivity [dr (cis/trans) = 59/41-83/17]. [Cu(II)PMDE-TA](2+) (PMDETA= N, N, N',N '',N ''-pentamethyldiethylenetriamine) which is much cheaper, albeit less reactive than [Cu(II)TPMA](2+), was also investigated but the results were not satisfactory.

Frenna, Vincenzo; Palumbo Piccionello, Antonio; Spinelli, Domenico; Ghelfi, Franco ( 2015 ) - On the rearrangement of some Z-arylhydrazones of 3-benzoyl-5-phenylisoxazoles into 2-aryl-4-phenacyl-2H-1,2,3-triazoles: a kinetic study of the substituent effects in Boulton-Katritzky reactions - TETRAHEDRON - n. volume 71 - pp. da 7315 a 7322 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The rearrangement of eight new Z-arylhydrazones of 3-benzoyl-5-phenylisoxazoles (3d–k) into the relevant 2-aryl-4-phenacyl-2H-1,2,3-triazoles (4d–k) in dioxane/water solution at different proton concentrations has been quantitatively studied in a wide temperature range (293–333 K). The data collected together with some our previous ones on compounds 3a–c have allowed a deep study of the substituent effects on the course of the rearrangement, thus increasing our knowledge on the Boulton–Katritzky reactions in isoxazole derivatives and on the temperature effects on free energy relationships.

A. J. Clark; A. Cornia; F. Felluga; A. Gennaro; F. Ghelfi; A. A. Isse; M. C. Menziani; F. Muniz-Miranda; F. Roncaglia; D. Spinelli ( 2014 ) - Arylsulfonyl Groups: The Best Cyclization Auxiliaries for the Preparation of ATRC γ-Lactams can be Acidolytically Removed - EUROPEAN JOURNAL OF ORGANIC CHEMISTRY - n. volume / - pp. da 6734 a 6745 ISSN: 1099-0690 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The N-arylsulfonyl group, which is the best and most useful cyclization auxiliary for the transition-metal-catalyzed atom transfer radical cyclization (ATRC) of N-allyl-α-polychloroamides, can be effectively removed from the target γ-lactams by using H2SO4–HOAc, without impairing the halogen functions. The reaction involves H+ attack on the aromatic moiety, and is strongly responsive to the electronic properties of the substituent bound to the aromatic ring: electron-donating groups, such as methyl or methoxy are, in fact, required for efficient “deprotection”. The N-p-nitrophenylsulfonyl cyclization auxiliary, in contrast to all the other sulfonyl groups tested, proved to be unsuitable for the ATRC, owing to a side reductive transposition that halts the redox cycle.

Roncaglia, Fabrizio; Ghelfi, Franco; Felluga, Fulvia; Poppi, Valentina ( 2014 ) - Simultaneous deprotection-oxidation of cyclic hemiacetals: A fine ending for a Ueno-Stork ATRC to dichloro-γ-lactones - TETRAHEDRON LETTERS - n. volume 55 - pp. da 2865 a 2868 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recently we found that a copper catalysed Ueno–Stork cyclization can be a very useful means for the expedient synthesis of dichloro-gamma-lactones, but, to take advantage of this step, the method still lacks of an efficient and selective follow-up. This Letter describes our progress in that field, unveiling the use of a supported and recyclable Cr(VI) catalyst for the simultaneous deprotection and oxidation of cyclic dichloro hemiacetals.

Frenna, V.; Palumbo Piccionello, A.; Cosimelli, B.; Ghelfi, Franco; Spinelli, D. ( 2014 ) - The Boulton–Katritzky Reaction: A Kinetic Study of the Effect of 5-Nitrogen Substituents on the Rearrangement of Some (Z)-Phenylhydrazones of 3-Benzoyl-1,2,4-oxadiazoles - EUROPEAN JOURNAL OF ORGANIC CHEMISTRY - n. volume / - pp. da 7006 a 7014 ISSN: 1099-0690 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The kinetics of the ring-into-ring conversion of some new (Z)-phenylhydrazones of 3-benzoyl-1,2,4-oxadiazole containing different nitrogen-substituents at C-5 (3b–d; X = NHMe, NMe2, and NHCOMe) into the relevant triazoles 4b–d have been examined in a wide range of pS+ (0.1–11.9) in 1:1 (v/v) dioxane/water solution. The obtained results have been compared with previous data concerning the (Z)-phenyl-hydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole (3a; X = NH2). All of the studied (Z)-phenylhydrazones rearrange through three different pathways (specific acid-catalysed, uncatalysed and general base-catalysed). The different effects of the substituents on the course of the rearrangement in the three pathways have been examined.

Franco Bellesia;Andrew J. Clark;Fulvia Felluga;Armando Gennaro;Abdirisak A. Isse;Fabrizio Roncaglia;Franco Ghelfi ( 2013 ) - Efficient and Green Route to γ-Lactams by Copper-Catalysed Reversed Atom Transfer Radical Cyclisation of α-Polychloro-N-allylamides, using a Low Load of Metal (0.5 mol%) - ADVANCED SYNTHESIS & CATALYSIS - n. volume 355 - pp. da 1649 a 1660 ISSN: 1615-4150 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The cyclisation of N-allyl-N-substituteda- polychloroamides is efficiently obtained through a copper-catalysed activators regenerated by electron transfer–atom transfer radical cyclisation process, with a metal load of only 0.5 mol%. The redox catalyst is introduced in its inactive form as copper( II) chloride/[nitrogen ligand] complex, and continuously regenerated to the active copper(I) chloride/[ nitrogen ligand] species by ascorbic acid. To preserve the catalyst integrity, the hydrochloric acid, released after each regeneration cycle, has been quenched by carbonate. The choice of the solvent is critical, the best performance being observed in ethyl acetate-ethanol (3:1).

Franco Bellesia; Seoung-ryoung Choi; Fulvia Felluga; Giuliano Fiscaletti; Franco Ghelfi; Maria Cristina Menziani; Andrew F. Parsons; C. Dale Poulter; Fabrizio Roncaglia; Massimo Sabbatini; Domenico Spinelli ( 2013 ) - Novel Route to Chaetomellic Acid A and Analogues: Serendipitous Discovery of a more Competent FTase Inhibitor - BIOORGANIC & MEDICINAL CHEMISTRY - n. volume 21 - pp. da 348 a 358 ISSN: 1464-3391 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A new practical route to chaetomellic acid A (ACA), based on the copper catalysed radical cyclization (RC) of (Z)-3-(2,2-dichloropropanoyl)-2-pentadecylidene-1,3-thiazinane, is described. Remarkably, the process entailed: (i) a one-pot preparation of the intermediate N-a-perchloroacyl-2-(Z)-alkyliden-1,3-thiazinanes starting from N-(3-hydroxypropyl)palmitamide, (ii) a two step smooth transformation of the RC products into ACA and (iii) only one intermediate chromatographic purification step. The method offers a versatile approach to the preparation of ACA analogues, through the synthesis of an intermediate maleic anhydride with a vinylic group at the end of the aliphatic tail, a function that can be transformed through a thiol–ene coupling. Serendipitously, the disodium salt of 2-(9-(butylthio)nonyl)-3-methylmaleic acid, that we prepared as a representative sulfurated ACA analogue, was a more competent FTase inhibitor than ACA. This behaviour was analysed by a molecular docking study.

L. Bianchi; F. Ghelfi; G. Giorgi; M. Maccagno; G. Petrillo; D. Spinelli; M. Stenta; C. Tavani ( 2013 ) - Uncommon 1,2-Migration of a Nitro Group Within a β-Nitrostyryl Moiety: Synthetic Scope and Mechanistic Details - EUROPEAN JOURNAL OF ORGANIC CHEMISTRY - n. volume / - pp. da 6298 a 6309 ISSN: 1099-0690 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The unusual migration of a nitro group from the β- to the α- position of a β-aryl-α-nitroethenyl moiety, following a nitrocyclopropane to isoxazoline N-oxide isomerization, has been studied from a mechanistic and synthetic points of view. As a result, two series of isomeric isoxazoline N-oxides could be obtained under controlled conditions. When reacted with diazomethane, a model transposed isoxazoline cleanly furnished a new, interesting pyrazolylisoxazole.

F. Bellesia; F. D’Anna; F. Felluga; V. Frenna; F. Ghelfi; A. F. Parsons; F. Reverberi; D. Spinelli ( 2012 ) - Breakthrough in the alpha-perchlorination of acyl chlorides - SYNTHESIS - n. volume 44(4) - pp. da 605 a 609 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The preparation of alpha-perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with Cl2, was efficiently achieved under base-catalysis using tetraalkylammonium chloride as a catalyst. The process is solvent-free and the procedure is easy, cheap and suitable for scale-up.

A. Cornia; F. Felluga; V. Frenna; F. Ghelfi; A. F. Parsons; M. Pattarozzi; F. Roncaglia; D. Spinelli ( 2012 ) - CuCl catalyzed radical cyclisation of N-alpha-perchloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides - TETRAHEDRON - n. volume 68 - pp. da 5863 a 5881 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The copper catalyzed radical cyclization (RC) of N-α-perchloroacyl cyclic ketene-N,X(X = O, NR, S)-acetals was studied. While the RC of N-acyl ketene-N,O-acetals was unsuccessful, the 5-endo cyclization provided much better results, with the following order of cyclization efficiency: hexa-atomic cyclic ketene-N,NR-acetals < penta-atomic cyclic ketene-N,S-acetals < hexa-atomic cyclic ketene-N,S-acetals. Invariably the catalytic cycle begins with the formation of a carbamoyl methyl radical. This leads to a cascade of reactions, including a radical polar crossover step, which ends with the formation of the maleimide nucleus, or precursors of this. Products from the RC of the hexa-atomic cyclic ketene-N,S-acetals, were efficiently transformed into disubstituted maleic anhydrides.

F. Felluga; C. Forzato; P. Nitti; G. Pitacco; F. Ghelfi; E. Valentin ( 2012 ) - First Chemoenzymatic Synthesis of (1)-2-Carboxypyrrolidine-3-AceticAcid, the Nucleus of Kainoid Amino Acids - CHIRALITY - n. volume 24 - pp. da 112 a 118 ISSN: 0899-0042 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The distinctive nucleus of kainoid amino acids, (2S,3R)-(1)-2-carboxypyrrolidine-3-acetic acid 6, was synthesized by a chemoenzymatic process, exploiting the diastereomeric cis/trans methyl pyroglutamate derivatives 10a–c/11a–c as key intermediates. These mixtures,when subjected to a kinetic resolution mediated by a-chymotrypsin, reacted diastereo-, regio-,and enantioselectively to give the trans derivatives (1)-10a–c possessing the correct (2S,3R) configuration.Subsequently, the desired product (2S,3R)-(1)-6 could be obtained after well-establishedtransformations.

R. Casolari; F. Felluga; V. Frenna; F. Ghelfi; U. M. Pagnoni; A. F. Parsons; D. Spinelli ( 2011 ) - A green way to γ-lactams through a copper catalyzed ARGET-ATRC in ethanol and in the presence of ascorbic acid - TETRAHEDRON - n. volume 67 - pp. da 408 a 416 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A “green” ARGET-ATRC, for the CuCl[PMDETA] catalysed cyclo-isomerization of N-allyl-alpha-polychloroamides to γ-lactams is described. The process works efficiently (yields 78-96%), uses a bio-solvent, as ethanol, and exploits the reducing feature of ascorbic acid to limit, at a low level (2-4%), the amount of catalyst. To preserve the efficacy of the catalytic cycle, addition of Na2CO3 is essential, which quenches the HCl released during the CuCl[PMDETA] regeneration step. Profitable features of the process are: mild reaction temperatures (25-37 °C), relatively short reaction times (usually 5 h) and low solvent volumes (2 mmoles of substrate/mL of ethanol). The method, upon stoichiometric adjustment, was also used for the synthesis of alpha,beta-unsaturated-γ-lactams from N-(2-chloroallyl)-alpha-polychloroamides, via a tandem process involving an ATRC and a reductive [1,2]-elimination.

F. Roncaglia; A. F. Parsons; F. Bellesia; F. Ghelfi ( 2011 ) - Acetic Anhydride/Et3N/DMAP: An Effective Acetylating System for Hemiacetals - SYNTHETIC COMMUNICATIONS - n. volume 41 - pp. da 1175 a 1180 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The selective and efficient acetylation of the hemiacetal hydroxyl in the equilibrium mixture between RCl2C(OAll)OH and AllOH/RCl2CHO was achieved using the acylating system Ac2O/Et3N/dimethylaminopyridine (DMAP).

F. D’Anna; V. Frenna; F. Ghelfi; S. Marullo; D. Spinelli ( 2011 ) - Acid- and Base-Catalysis in the Mononuclear Rearrangement of Some (Z)-Arylhydrazones of 5-Amino-3-benzoyl-1,2,4-oxadiazole in Toluene: Effect of Substituents on the Course of Reaction - JOURNAL OF ORGANIC CHEMISTRY - n. volume 76 - pp. da 2672 a 2679 ISSN: 0022-3263 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction rates for the rearrangement of eleven(Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole 3a-kinto the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas4a-k in the presence of trichloroacetic acid or of piperidinehave been determined in toluene at 313.1 K. The results havebeen related to the effect of the aryl substituent by usingHammett and/or Ingold-Yukawa-Tsuno correlations andhave been compared with those previously collected in a proticpolar solvent (dioxane/water) as well as with those on theanalogous rearrangement of the corresponding (Z)-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole 1a-k in benzene. Some light can thus be shed on the general differences of chemical reactivity between protic polar (or dipolar aprotic) and apolar solvents.

M. Bregoli; F. Felluga; V. Frenna; F. Ghelfi; U. M. Pagnoni; A. F. Parsons; G. Petrillo; D. Spinelli ( 2011 ) - Synthesis of 3-Alkyl-4-(chloromethyl)-1-RSO2-1H-pyrrol-2(5H)-ones, Using a Sequential ATRC/[1,2]-Elimination, from 2,2-Dichloro-N-(2-chloroallyl)-NRSO2-amides - SYNTHESIS - n. volume - - pp. da 1267 a 1278 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The preparation of 3-alkyl-4-(chloromethyl)-1-RSO2-1H-pyrrol-2(5H)-ones was efficiently accomplished through a[1,2]-elimination of g-lactams derived from the copper(I)-catalysed ATRC of 2,2-dichloro-N-(2-chloroallyl)-N-RSO2-amides. The two reactions can be integrated into a sequential one-pot process.

D’Anna, F.; Frenna, V.; Ghelfi, Franco; Macaluso, G.; Marullo, S.; Spinelli, D. ( 2010 ) - Apolar versus Polar Solvents: A Comparison of the Strength of Some Organic Acids againstDifferent Bases in Toluene and in Water - JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY - n. volume 114 - pp. da 10969 a 10974 ISSN: 1089-5639 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The constants of ion-pair formation with 3-nitroaniline (3NO2A) for eight halogenoacetic acids (HAAs, 3a-h:TFA, TCA, TBA, DFA, DCA, DBA, MCA, and MBA), and five 2,2-dichloroalkanoic acids containing 3-8carbon atoms (HAs, 5a-e: DCPA, DCBA, DCMBA, DCVA, and DCOA) have been determined in TOL at298.1 K. The results obtained brought to evidence for HAAs the formation of ion-pairs with two differentstoichiometries (base-acid, 1:1 or 1:2), while in contrast the HAs furnish only the 1:1 pairs. The differentsteric and electronic requirements of HAAs and HAs seem to be responsible for such an unlikely behavior.At the same time, the acid-catalyzed MRH of the (Z)-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole(1) into (2,5-diphenyl-2H-1,2,3-triazol-4-yl)urea (2) in the presence of the five HAs above has been investigatedin TOL at 313.1 K. Thus, in contrast with previous results in the presence of several HAAs, a unique pathwayfor the rearrangement has been observed, again pointing out the importance of the above effects on the initialacid/base interactions. Finally the acidic strength of TFA against seven nitroanilines (NA, 4a-g: 4NO2A,3NO2A, 3Me4NO2A, 4Me3NO2A, 2Me3NO2A, 2NO2A, and 3,5diNO2A) characterized by a very differentbasicity has been measured in TOL at 298.1 K.

Felluga, F.; Ghelfi, Franco; Pitacco, G.; Roncaglia, Fabrizio; Valentin, E.; Venneri, C. D. ( 2010 ) - Esterase-mediated synthesis of optically active GABA analogues containing a stereogenic all-carbon quaternary carbon atom. - TETRAHEDRON-ASYMMETRY - n. volume 21 - pp. da 2183 a 2191 ISSN: 0957-4166 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Esterase from Horse Liver (HLAP) was able to hydrolyze a series of linear and cyclic b,b-dialkyl-c-nitroesters, in spite of the well-known reluctance of hydrolytic enzymes to recognize and transform hindered substrates, such as those possessing a stereogenic quaternary carbon atom next to the reaction site. The resulting optically active c-nitroesters gave access to optically active b,b-disubstituted c-aminoacids as well as a,a-disubstituted succinic acids, both being biologically relevant compounds.

Ghelfi, Franco; Pattarozzi, Mariella; Roncaglia, Fabrizio; Giangiordano, Valerio; Parsons, A. F. ( 2010 ) - Expedient Synthesis, on Large Scale, of Aliphatic Chaetomellic Anhydrides from N-Allyl-2,2-dichlorocarboxyamides - SYNTHETIC COMMUNICATIONS - n. volume 40 - pp. da 1040 a 1051 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Chaetomellic anhydride A and an analog (with two addnl. carbons) were obtained, on a preparative scale, starting from amides derived from the acylation of 2-(2-propenylamino)pyridine with 2,2-dichloropalmitic or 2,2-dichlorostearic acid. An alternative approach, in which the Me substituent of the target anhydride is introduced by the carboxylic acid reactant and the long aliph. chain is added through the allylamino moiety, proved unviable.

Pattarozzi, Mariella; Roncaglia, Fabrizio; Accorsi, L.; Parsons, A. F.; Ghelfi, Franco ( 2010 ) - Functional rearrangement of 3-Cl or 3,3-diCl-γ-lactams bearing a secondary 1-chloroalkyl substituent at C-4 - TETRAHEDRON - n. volume 66 - pp. da 1357 a 1364 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The study of the reaction with MeONa/MeOH of chlorinated , prepd. from the atom transfer radical cyclization of N-allyl-α-perchloroamides, has been extended to the case of substrates carrying an exo halogen atom on a branched carbon. Only with secondary exo C-Cl groups, that are not located on a fused ring, does the functional rearrangement follow the typical transformation route, which with trichloro-lactams can proceed further to give 4-alkylidene derivs. From a practical point of view, the outcome of the reaction with di- or trichloro N-cinnamylamides is synthetically valuable, affording the 5-methoxy-1H-pyrrol-2(5H)-one or 3-benzylidenepyrrolidine-2,5-dione, resp., in good to excellent yield.

M. Pattarozzi; F. Roncaglia; V. Giangiordano; P. Davoli; F. Prati; F. Ghelfi. ( 2010 ) - 'Ligand-free-like' CuCl-catalyzed atom transfer radical cyclization of N-substituted N-allyl polychloroamides to γ-lactams. - SYNTHESIS - n. volume - - pp. da 694 a 700 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Atom transfer radical cyclization (ATRC) of N-alkyl N-allyl dichloroamides to γ-lactams, catalyzed by 'naked' CuCl, worked efficiently in DMF, whereas, when the same dichloroamides were N-sulfonylated, DMF needed to be replaced by acetonitrile. The outcome of the cycloisomerization with N-substituted N-allyl trichloroacetamides was less affected by solvent choice, although for an effective reaction to occur, the solvent had to dissolve the cuprous salt. Catalyst loading ranged between 5 and 20 mol%.

F. Roncaglia; C. V. Stevens; F. Ghelfi; M. Van der Steen; M. Pattarozzi; L. De Buyck ( 2009 ) - A new synthetic route to Tyromycin A and its analogue from renewable resources - TETRAHEDRON - n. volume 65 - pp. da 1481 a 1487 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The synthesis of tyromycin A and that of the non-natural lower homologue, involving as featuring stepsa transition metal catalyzed atom transfer radical cyclization and a functional rearrangement of thepolyhalogenated 2-pyrrolidinones thus obtained, are described. Both routes use 10-undecenoic acid,a renewable source from castor oil, as starting material for the preparation of the pivotal intermediatesa,a,a0,a0-tetrachlorodicarboxylic acids.

F. Ghelfi; F. Roncaglia; M. Pattarozzi; V. Giangiordano; G. Petrillo; F. Sancassan; A. F. Parsons. ( 2009 ) - Atom transfer radical cyclization of O-allyl-2,2-dichlorohemiacetal acetates: an expedient method to dichloro-gamma-lactones. - TETRAHEDRON - n. volume 65 - pp. da 10323 a 10333 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

3-Alkyl-3-chloro-4-chloromethyl--lactones were synthesized in acceptable yields, exploiting the CuCl-N,N,N’,N”,N”-pentamethyldiethylenetriamine catalyzed atom transfer radical cyclization (ATRC) of O-allyl-2,2-dichlorohemiacetal acetates, starting materials easily prepared from 2,2-dichloroaldehydes. The oxidation of the intermediate dichloro-2-acetoxytetrahydrofurans was completed in a two step, one-pot procedure: hydrolysis to gamma-lactol and final oxidation to lactone with the Jones’ reagent.

Pattarozzi, Mariella; Ghelfi, Franco; Roncaglia, Fabrizio; Pagnoni, Ugo Maria; Parsons, A. F. ( 2009 ) - Synthesis of the disubstituted maleic anhydride frame using a novel tandem radical-polar reaction - SYNLETT - n. volume 00 - pp. da 2172 a 2176 ISSN: 0936-5214 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An unreported 5-endo-trig atom transfer radical cyclization of cyclic N--dichloroacyl-ketene-N,S-acetals, which evolves as a tandem radical-polar process, is described. The reaction, which is carried out in the presence of a Cu(I) complex catalyst (10 mol%) and an inorganic base (i.e. carbonate), can be exploited as the key step for a novel, short and versatile synthesis of the 3,4-disubstituted maleic anhydride nucleus.

F. Ghelfi; M. Pattarozzi; F. Roncaglia; A.F. Parsons; F. Felluga; U.M. Pagnoni; E. Valentin; A. Mucci; F. Bellesia ( 2008 ) - Preparation of the Maleic Anhydride Nucleus from Dichloro γ-Lactams: Focus on the Role of the N-Substituent in the Functional Rearrangement and in the Hydrolytic Steps - SYNTHESIS - n. volume 19 - pp. da 3131 a 3141 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The preparation of the 3,4-dialkyl-substituted maleic anhydride nucleus, through the functional rearrangement of dichloro γ-lactams, allowed the comparison of various N-substituents in the functional rearrangement step. The 2-pyridyl group proved to be the most appropriate N-substituent for the hydrolysis of the 5-methoxy-1,5-dihydro-2H-pyrrol-2-one intermediate into the 5-hydroxy adduct, and for the hydrolysis of the maleimide nucleus into the maleic anhydride. The oxidation of the 5-hydroxy-1,5-dihydro-2H-pyrrol-2-one into the corresponding maleimide was achieved with manganese(IV) oxide.

MONTGOMERY I.; PARSONS A. F.; F. GHELFI; F. RONCAGLIA ( 2008 ) - Radical initiation using borole derivatives (Elsevier Science Limited:Oxford Fulfillment Center, PO Box 800, Kidlington Oxford OX5 1DX United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: asianfo@elsevier.com, tcb@elsevier.co.UK, INTERNET: http://www.elsevier.com, http://www.elsevier.com/locate/shpsa/, Fax: 011 44 1865 843010 ) - TETRAHEDRON LETTERS - n. volume 49 - pp. da 628 a 630 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

2-Propylbenzo[d][1,3,2]dioxaborole and related derivatives are shown to initiate a range of radical reactions under mild conditions.

M. Van der Steen; C.V. Stevens; Y. Eeckhout; L. De Buyck; F. Ghelfi; F. Roncaglia ( 2008 ) - Undecylenic acid: a valuable renewable Building Block on route to Tyromycin A derivatives - EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY - n. volume 110 - pp. da 846 a 852 ISSN: 1438-9312 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A key intermediate for the synthesis of Tyromycin A, a C-20 tetrachlorodicarboxylic acid, was produced in six steps starting with a dimerisation of methyl 10-undecenoate which was obtained from a renewable resource, e.g. castor oil. The acyloin condensation product was then oxidised, transformed to the diene, followed by ozonisation, chlorination and finally oxidation to the corresponding tetrachlorodicarboxylic acid.

F. FELLUGA; F. GHELFI; UM PAGNONI; AF PARSONS; M. PATTAROZZI; F. RONCAGLIA; E. VALENTIN ( 2007 ) - A novel short approach to (Z)-pulchellalactam through Transition-Metal-Catalized Atom-Transfer Radical Cyclization of 1-isopropylprop-2-enyl dichloroacetate - SYNTHESIS - n. volume 00 - pp. da 1882 a 1886 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A new five-step route to the CD45 protein tyrosine phosphatase inhibitor (Z)-pulchellalactam is presented. Key steps are the CuCl-bipyridine catalysed atom transfer radical cyclization of an appropriate allyl ,-dichloroacetate and the subsequent dehydrochlorination/prototropic rearrangement of the resulting dichlorolactone.

FELLUGA F; FORZATO C; F. GHELFI; NITTI P; PITACCO G; PAGNONI U. M; RONCAGLIA F ( 2007 ) - Atom Tranfer Radical Cyclization (ATRC) applied to a chemo-enzymatic synthesis of Quercus Lactones - TETRAHEDRON-ASYMMETRY - n. volume 18 - pp. da 527 a 536 ISSN: 0957-4166 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The natural fragrances (+)-trans whisky lactone 2 and (+)-trans cognac lactone 4, together with a minor amount of their ()-cis stereoisomers, were prepared in 50% and 42% overall yield, respectively, starting from racemic 1-hepten-3-ol (±)-5 and 1-octen-3-ol(±)-6. The procedure involved first the enantioconvergent, lipase mediated transformation of the secondary allylic alcohols deriveddichloroacetates (±)-7 and (±)-8 into the corresponding homochiral (+)-7 and (+)-8, combined with their cyclization under a transitionmetal catalyzed atom transfer process.

C. FORZATO; G. FURLAN; F. GHELFI; P. NITTI; G. PITACCO; F. RONCAGLIA; E. VALENTIN ( 2007 ) - Lipase-catalysed deacetylation of botryodiplodin acetate (PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND, OX5 1GB ) - TETRAHEDRON-ASYMMETRY - n. volume 18 - pp. da 447 a 450 ISSN: 0957-4166 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Enantioselective deacetylation of -(±)-botryodiplodin acetate was successfully accomplished by means of Lipase PS to afford -(+)-botryodiplodin and -(+)-botryodiplodin acetate with high enantiomeric excesses. Enzyme-mediated transesterification of the acetylated molecule with n-butanol as well as its hydrolysis in several organic solvents are also reported. The CD spectra of -(+)-botryodiplodin and -(+)-botryodiplodin acetate are also presented.

L. DE BUYCK; C. FORZATO; F. GHELFI; A. MUCCI; P. NITTI; UM PAGNONI; AF PARSONS; G. PITACCO; F. RONCAGLIA ( 2006 ) - A new and effective route to (+/-)-botryodiplodin and (+/-)-epi-botryodiplodin acetates using a halogen atom transfer Ueno-Stork cyclization - TETRAHEDRON LETTERS - n. volume 47 - pp. da 7759 a 7762 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

(+/-)-Botryodiplodin and (+/-)-epi-botryodiplodin acetates were prepared in good yields following a practical four step route. The method, for the construction of the strategic tetrahydrofuran ring, hinged on an unprecedented halogen atom transfer Ueno-Stork cyclization of an O-allyl alpha,alpha-dihalohemiacetal acetate, catalyzed by the redox complex CuCl/N,N,N ',N '',N ''-pentamethyldiethylenetriamine. (c) 2006 Elsevier Ltd. All rights reserved.

F. Bellesia; C. Danieli; L. De Buyck; R. Galeazzi; F. Ghelfi;A. Mucci; M. Orena; U. M. Pagnoni; A. F. Parsons; F. Roncaglia ( 2006 ) - A short approach to chaetomellic anhydride A from2,2-dichloropalmitic acid: elucidation of the mechanism governingthe functional rearrangement of the chlorinatedpyrrolidin-2-one intermediate - TETRAHEDRON - n. volume 62 - pp. da 746 a 757 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Chaetomellic anhydride A was efficiently attained in three steps, starting from 2,2-dichloropalmitic acid and 2-(3-chloro-2-propenylamino)pyridine. Atom transfer radical cyclisation selectively formed the cis-stereoisomer of the trichloropyrrolidin-2-one, which underwent a stereospecific functional rearrangement to form a substituted maleimide. The choice of 2-pyridyl, as ‘cyclisation auxiliary’ in the atom transfer radical cyclisation step, proved beneficial for hydrolysis of the maleimide to form the desired anhydride.

L. De Buyck; C. Danieli; F. Ghelfi; UM Pagnoni; AF Parsons; M. Pattarozzi; F. Roncaglia ( 2005 ) - A new route to (±)-erythro-roccellic acid and chaetomellic anhydride C through functional rearrangement, promoted by n-propylamine or CH3ONa/CH3OH, of N-propyl-3-chloro-4-dichloromethyl-3-dodecylpyrrolidin-2-one - TETRAHEDRON - n. volume 61 - pp. da 2871 a 2877 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The rearrangement of a trichloro-pyrrolidin-2-one, prepared by the CuCl-TMEDA catalyzed atom transfer radical cyclization of N-alkyl-N-(3-chloro-2-propenyl)-2,2-dichloromyristamide, with n-propylamine or CH3ONa/CH3OH, is the key step of a new, short and inexpensive route to chaetomellic anhydride C and (+/-)-erythro-roccellic acid.

F. Roncaglia; L. De Buyck; F. Bellesia; C. Forzato; F. Ghelfi; L. Goldoni; A. Mucci; U. M. Pagnoni; A. F. Parsons; E. Valentin ( 2005 ) - Nuova sintesi della (+/-)-Botriodiplodina attraverso ciclizzazione di Ueno-Stork a trasferimento di atomo ( 5° Sigma Aldrich Young Chemists Symposium - Riccione - 10-12 ottobre 2005) ( - 5° Sigma Aldrich Young Chemists Symposium ) (SAYCS Riccione ITA ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

E' presentata una nuova sintesi della (+/-)-Botriodiplodina attraverso ciclizzazione di Ueno-Stork a trasferimento di atomo

F. Roncaglia; L. De Buyck; F. Bellesia; C. Forzato; F. Ghelfi; L. Goldoni; A. Mucci; U. M. Pagnoni; A. F. Parsons; E. Valentin ( 2005 ) - Sintesi della (+/-)-Botriodiplodina e della sua forma Epi attraverso una ciclizzazione di Ueno-Stork a trasferimento di atomo ( III Meeting Prin 2003-2004 - Riccione - 12-13 ottobre 2005) ( - III Meeting Prin 2003-2004 ) (.. .. ITA ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

E' riportata la sintesi della (+/-)-botriodiplodina e della sua forma Epi attraverso una ciclizzazione di Ueno-Stork a trasferimento di atomo

L. De Buyck; F. Ghelfi; A. Mucci; U. M. Pagnoni; A. F. Parsons; A. Pinetti; F. Roncaglia ( 2005 ) - Studio di una via più versatile per la preparazione di nuclei 2,5-furandionici disostituiti ( III Meeting Prin 2003-2004 - Riccione - 12-13 ottobre 2005) ( - III Meeting Prin 2003-2004 ) (.. .. ITA ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Si riporta lo studio di una via più versatile per la preparazione di nuclei 2,5-furandionici disostituiti

L. De Buyck; R. Cagnoli; F. Ghelfi; G. Merighi; A. Mucci; U.M. Pagnoni; A.F. Parsons ( 2004 ) - A simple and efficient route to chaetomellic anhydride A: A potent natural Ras farnesyl-protein transferase inhibitor (Georg Thieme Verlag Stuttgart:Postfach 301120, D-70451 Stuttgart Germany:011 49 711 8931321, EMAIL: aboservice@thieme.de, INTERNET: http://www.thieme.de, Fax: 011 49 711 8931422 ) - SYNTHESIS - n. volume 2004 - pp. da 1680 a 1686 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A new and efficient approach to chaetomellic anhydride A has been devised starting from 2,2-dichloropalmitic acid. This involves the atom transfer radical cyclization of an N-alkyl-N-(3-chloro-2-propenyl)amide followed by rearrangement of the resulting trichloro-pyrrolidin-2-one.

C. Danieli; F. Ghelfi; A. Mucci; U. M. Pagnoni; A. F. Parsons;M. Pattarozzi; L. Schenetti ( 2004 ) - Functional rearrangement of polychlorinated pyrrolidin-2-onesto 5-imino-lactams promoted by n-propylamine - TETRAHEDRON - n. volume 60 - pp. da 11493 a 11501 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Abstract—The reaction of 4-methyl-pyrrolidin-2-ones, chlorinated at the C(3) and C(6) positions, with n-propylamine constitutes a new method for the preparation of 5-propylimino-pyrrolidin-2-ones or 3-pyrrolin-2-ones in generally good yields. The transformation involves a series of eliminations, substitutions and double bond shifts. This constitutes a remarkable example of a functional rearrangement.

F. Bellesia; L. De Buyck; F. Ghelfi; UM Pagnoni; P. Strazzolini ( 2004 ) - Oxidation of aliphatic 2,2-dichloroalkanals by HNO3 in CH2Cl2: An easy and eco-friendly route to the corresponding 2,2-dichloroalkanoic acids - SYNTHETIC COMMUNICATIONS - n. volume 34 - pp. da 1473 a 1481 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A simple, economically convenient, and eco-compatible procedure for the oxidation of 2,2-dichloroalkanals to the corresponding alkanoic acids has been set up, employing HNO3 in CH2Cl2, in the presence of NaNO2 as catalyst.

L. De Buyck; C. Danieli; F. Ghelfi; A. Mucci; U. M. Pagnoni; A. Pinetti; A. F. Parsons ( 2004 ) - Sintesi dell’acido chetomellico A, un antitumorale naturale inibitore della RAS farnesil-protein transferasi (FPTasi) ( II Meeting Prin 2001-2004 - Riccione - 28-31 ottobre 2004) ( - II Meeting Prin 2001-2004 ) (.. .. ITA ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Si propone una nuova via sintetica per l'ottenimento dell’acido chetomellico A.

L. De Buyck; F. Ghelfi; A. Mucci; U. M. Pagnoni; N. Dieltiens; A. F. Parsons ( 2004 ) - Synthetic utility of 2,2-dichlorocarboxylic acids ( Belgian Organic Synthesis Symposium (B.O.S.S.) - Louvrin-La-Neuve (Belgium) - 12-16 July 2004) ( - Belgian Organic Synthesis Symposium (B.O.S.S.) - book of abstracts ) (BOSS Louvrin-La-Neuve BEL ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

The synthetic utility of derivatives of 2,2-dichlorocarboxylic acids in radical cyclization reactions is shown.

F. Bellesia; L. De Buyck; F. Ghelfi; UM Pagnoni; AF Parsons; A. Pinetti ( 2003 ) - An efficient route to aliphatic 2,2-dichloroaldehydes via chlorination of aldehydes or alcohols with the system Cl-2/quaternary ammonium chloride - SYNTHESIS - n. volume 14 - pp. da 2173 a 2178 ISSN: 0039-7881 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An effective and low waste method for preparing aliphatic 2,2-dichloroaldehydes has been achieved by halogenation of aldehydes or alcohols with Cl-2, using tetraalkylammonium chlorides as recoverable catalysts.

R. CAGNOLI; F. GHELFI; UM PAGNONI; AF PARSONS; L. SCHENETTI ( 2003 ) - Hydro-de-halogenation and consecutive deprotection of chlorinated N-amido-pyrrolidin-2-ones with Raney-Ni: an effective approach to gabapentin - TETRAHEDRON - n. volume 59 - pp. da 9951 a 9960 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The benzoylamino group was identified as a useful radical cyclization auxiliary that can be smoothly removed on hydro-dehalogenation of chlorinated N-substituted-pyrrolidin-2-ones with Raney-Ni. This methodology was successfully implemented in a new and appealing route to the anti-epileptic drug gabapentin.

Bryans JS; Chessum NEA; Huther N; Parsons AF; Ghelfi F ( 2003 ) - Metal-catalysed radical cyclisations leading to N-heterocycles: new approaches to gabapentin and pulchellalactam - TETRAHEDRON - n. volume 59 - pp. da 6221 a 6231 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The copper(I) or ruthenium(II)-mediated radical cyclisation of halo-amides has been utilised to afford functionalised pyrrolidinones via 5-endo-trig or 5-exo-trig radical cyclisation pathways. This methodology has been applied to novel and concise syntheses of the anti-epileptic drug gabapentin and the biologically active natural product pulchellalactam.

L. De Buyck; F. Bellesia; F. Ghelfi; G. Merighi; A. Mucci; U. M. Pagnoni; A. Pinetti; A. F. Parsons ( 2003 ) - Sintesi semplificata dell’acido chetomellico A, antitumorale naturale inibitore della Ras farnesil-protein transferasi ( XXI Congresso SCI - Torino - 22-27 giugno 2003) ( - XXI Congresso SCI - ATTI ) (SCI Torino ITA ) - n. volume unico [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

E' riportata una sintesi semplificata dell’acido chetomellico A, antitumorale naturale inibitore della Ras farnesil-protein transferasi.

F. Ghelfi; CV Stevens; I. Laureyn; E. Van Meenen; TM Rogge; L. De Buyck; K V Nikitin; R. Grandi; E. Libertini; UM Pagnoni; L. Schenetti ( 2003 ) - Synthesis of 5-methoxylated 3-pyrrolin-2-one via the rearrangement of chlorinated pyrrolidin-2-ones - TETRAHEDRON - n. volume 59 - pp. da 1147 a 1157 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of N-substituted 4-methyl-2-pyrrolidinones or 4-diethoxyphosphoryl analogues, carrying at least two chlorine atoms between the C(3) and C(6) carbons, with alkaline methoxide in methanol afforded the corresponding 5-methoxylated 3-pyrrolin-2-ones, useful adducts for the preparation of agrochemicals or medicinal compounds. (C) 2003 Elsevier Science Ltd. All rights reserved.

M.E. CASARINI; F. GHELFI; E. LIBERTINI; U.M. PAGNONI; A.F. PARSONS ( 2002 ) - 1,2-reduction of alpha,beta-unsaturated hydrazones using dimethylamine-borane/p-toluenesulfonic acid: an easy route to allyl hydrazines - TETRAHEDRON - n. volume 58 - pp. da 7925 a 7932 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

alpha,beta-Unsaturated hydrazones can be easily converted into N-allyl hydrazines by reaction with dimethylamine-borane/p-toluenesulfonic acid under mild reaction conditions. The reduction works well for N'-allyhydrazides but N'-allyl-N,N-dimethylhydrazines are rapidly reoxidised by air and so need to be manipulated under an inert atmosphere prior to M-acylation. Competitive conjugate reduction can also be observed and the regioselectivity of the dimethylamine-borane attack is determined by steric and/or electronic factors. The procedure is also effective for the C=N reduction of unconjugated hydrazones. (C) 2002 Elsevier Science Ltd. All rights reserved.

F. GHELFI; AF PARSONS; D. TOMMASINI; A. MUCCI ( 2001 ) - Intramolecular Diels-Alder cycloaddition of N-allyl-N-(2-furylmethyl)amides - First step of a new route towards the synthesis of a densely functionalized pyrrolizidine ring - EUROPEAN JOURNAL OF ORGANIC CHEMISTRY - n. volume 2001 - pp. da 1845 a 1852 ISSN: 1434-193X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The intramolecular Diels-Alder reaction of N-allyl-N-(2-furylmethyl)amides to exo-N-acyl-3-aza-10-oxatricyclo[5.2.1.0(1)-,5]dec-8-enes is described. The cycloaddition is controlled not only by the size of the amide appendage, but, also by electronegativity of the amide. An example of a new approach towards the synthesis of a highly functionalized pyrrolizidine ring, which links this Diels-Alder cycloaddition to an halogen atom transfer radical cyclization, is reported.

M. Borsari; C. Gabbi; F. Ghelfi; R. Grandi; M. Saladini; S. Severi; F. Borella ( 2001 ) - Silybin, a new iron-chelating agent - JOURNAL OF INORGANIC BIOCHEMISTRY - n. volume 85 - pp. da 123 a 129 ISSN: 0162-0134 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silybin, a natural occurring flavolignan isolated from the fruits of Silibum marianum, has been reported to exert antioxidant and free radical scavenging abilities. It was suggested to act also as an iron chelator. The complexation and protonation equilibria of the ferric complex of this compound have been studied by potentiometric, spectrophotometric and electrochemical techniques. The formation of the complex silybin-Ga(III) in anhydrous DMSO-d6 has been studied by H-1 NMR spectroscopy. Mass spectrometry and infrared spectroscopy on silybin-Fe(III) complex confirm all data obtained by H-1 NMR spectroscopy. The experimental results show that silybin binds Fe(III) even at acidic pH. Different ternary complexes were observed at increasing methoxide ion concentration and their stability constants have been calculated. The results show the possible role of silybin in relation to the chelation therapy of chronic iron overload, as occurs in the treatment of Cooley's anemia. (C) 2001 Elsevier Science B.V. All rights reserved.

Bryans JS; Chessum NEA; Parsons AF; Ghelfi F ( 2001 ) - The synthesis of functionalised beta- and gamma-lactams by cyclisation of enamides using copper(I) or ruthenium(II) - TETRAHEDRON LETTERS - n. volume 42 - pp. da 2901 a 2905 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cyclisation of a variety of halo-enamides with copper(I) or ruthenium(II) complexes has been investigated. The regioselectivity of the radical cyclisation, which can proceed via either a 4-exo or 5-endo pathway, to form beta- or gamma -lactam products respectively, is determined by the nature of the metal oxidant and the reaction conditions. Thus, whereas copper(I)bipyridine reactions give predominantly gamma -lactams, the use of copper(I)/TMEDA or dichlorotris(triphenylphosphine)ruthenium(II) affords mainly beta -lactams. (C) 2001 Elsevier Science Ltd. All rights reserved.

F. BELLESIA; L. DE BUYCK; M.V. COLUCCI; F. GHELFI; I. LAUREYN; E. LIBERTINI; A. MUCCI; U.M. PAGNONI; A. PINETTI; T.M. ROGGE; C.V. STEVENS ( 2001 ) - Unusual access to 5-methoxy or 5,5-dimethoxy-4-methyl-3-pyrrolin-2-ones from chlorinated 4-methyl-pyrrolidin-2-ones (Elsevier Science Limited:Oxford Fulfillment Center, PO Box 800, Kidlington Oxford OX5 1DX United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: asianfo@elsevier.com, tcb@elsevier.co.UK, INTERNET: http://www.elsevier.com, http://www.elsevier.com/locate/shpsa/, Fax: 011 44 1865 843010 ) - TETRAHEDRON LETTERS - n. volume 42 - pp. da 4573 a 4575 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reaction of N-substituted 4-methyl-2-pyrrolidinones, carrying not less than two chlorine atoms on the C(3) and C(6) carbons afforded with alkaline methoxide in methanol, under mild conditions, the corresponding 5-methoxy or 5,5-dimethoxy-4-methyl-3-pyrrolin-2-ones in satisfactory yields.

Ghelfi F; Parsons AF ( 2000 ) - N,N-(dimethylamino)-2-pyrrolidinones from the rearrangement of N-allyl-N ',N '-dimethyl-2,2-dichlorohydrazides promoted by CuCl-N,N,N ',N '-tetramethylethylendiamine - JOURNAL OF ORGANIC CHEMISTRY - n. volume 65 - pp. da 6249 a 6253 ISSN: 0022-3263 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Treatment of N-allyl-N¢,N¢-dimethyl-2,2-dichlorohydrazides with CuCl/TMEDA in ethyl acetate35is a mild and easy method for preparing N-(dimethylamino)-2-pyrrolidinones. As the N-N bond in the lactamproducts can be easily and efficiently cleaved, this makesN-dimethylamino protection an attractive alternative toN-benzylic protection.

F. Bellesia; L. De Buyck; F. Ghelfi; E. Libertini; UM Pagnoni; F. Roncaglia ( 2000 ) - 2,2-dichlorination of aldehydes with the 2,6-lutidine center dot HCl/Cl-2/CH2Cl2 system: An environmentally benign process suitable for scale up - TETRAHEDRON - n. volume 56 - pp. da 7507 a 7511 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An effective and environmentally benign preparation of 2,2-dichloroaldehydes has been achieved by chlorination of aldehydes with Cl-2(g) in CH2Cl2, using 2,6-lutidine hydrochloride as recoverable catalyst. Remarkable qualities of the process are: easy work up, high purity products, HCl as the only 'waste' stream and inherent bias to the scale up. (C) 2000 Elsevier Science Ltd. All rights reserved.

F. Ghelfi; F. Bellesia; L. De Buyck ( 2000 ) - 2,2-Dichloroaldehydes and 2,2-dichlorocarboxylic acids from 2-picoline center dot HCl catalyzed chlorination of aldehydes - SYNLETT - n. volume 00 - pp. da 146 a 148 ISSN: 0936-5214 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An efficient preparation of 2,2-dichloroaldehydes and 2,2-dichlorocarboxylic acids has been achieved by chlorination of aldehydes using 2-picoline hydrochloride as recoverable catalyst.

L. Forti; F. Ghelfi; S. Levizzani; U.M. Pagnoni ( 1999 ) - Conformationally constrained amino acids: A convenient approach to cis-2,3-methano-GABAs - TETRAHEDRON LETTERS - n. volume 40 - pp. da 3233 a 3234 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

3-Aza-2-oxo-bicyclo[3.1.0]hexanes, which are opened to 2,3-methano-gamma-aminobutyric acids, are obtained in very high yields by a two step procedure from N-protected-N-allyl-alpha-Br-amides. (C) 1999 Elsevier Science Ltd. All rights reserved.

F. Ghelfi; G. Ghirardini; E. Libertini; L. Forti; U.M. Pagnoni ( 1999 ) - Easy approach to 3-benzylimino-2-pyrrolidinones from 3-chloro-4-chloromethyl-2-pyrrolidinones - TETRAHEDRON LETTERS - n. volume 40 - pp. da 8595 a 8597 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

3-Benzylimino-2-pyrrolidinones can be prepared in good yield by heating 3-chloro-4-chloromethyl-2-pyrrolidinones, benzylamine and NaI in THF at 80 degrees C. An endo-dehydrohalogenation followed by a SN2' substitution on the intermediate allyl chloride, and finally a shift of the exo-double bond to Delta(3) with attendant tautomerization, appears to be the most probable reaction mechanism. (C) 1999 Elsevier Science Ltd. All rights reserved.

F. Bellesia; L. Forti; F. Ghelfi; G. Ghirardini; E. Libertini; U.M. Pagnoni; A. Pinetti; N. Prochilo ( 1999 ) - Rearrangement of N-allyl-alpha,alpha-dichloroamides, beta- or gamma-functionalized, to substituted analogues of the gamma-aminobutyric acid (GABA) - SYNTHETIC COMMUNICATIONS - n. volume 29 - pp. da 3739 a 3748 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The rearrangement of gamma-chloro, beta-hydroxy or beta-vinyl N-allyl-N-benzyl-alpha,alpha-dichlorocarboxyamides to gamma-aminobutyric acid analogues is efficiently promoted by CuCl\N,N,N',N'-tetramethylethylendiamine. With the beta-vinyl functionalization a tandem radical-radical reaction, yielding 3-aza-2-oxo-bicyclo[3,3,0]octane adducts, is also observed.

F. Ghelfi; F. Bellesia; L. Forti; G. Ghirardini; R. Grandi; E. Libertini; M.C. Montemaggi; U.M. Pagnoni; A. Pinetti; L. De Buyck; A.F. Parson ( 1999 ) - The influence of benzylic protection and allylic substituents on the CuCl-TMEDA catalyzed rearrangement of N-allyl-N-benzyl-2,2-dihaloamides to gamma-lactams. Application to the stereoselective synthesis of pilolactam. - TETRAHEDRON - n. volume 55 - pp. da 5839 a 5852 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A number of N-benzylic protecting groups and allylic substituents have been investigated for the rearrangement, promoted by CuCl-TMEDA, of N-allyl-2,2-dihaloamides to 3,4-disubstituted gamma-lactams. An appreciable chiral induction was observed at the C-4 site when alpha-phenylethylamine was used as a chiral protecting group, while an unexpected Diels-Alder reaction occurred when using a 2-furyl-methyl protection. This rearrangement has been applied to the synthesis of pilolactam, a drug with muscarinic activity. (C) 1999 Elsevier Science Ltd. All rights reserved.

F. Bellesia; L. Forti; E. Gallini; F. Ghelfi; E. Libertini; U.M. Pagnoni ( 1998 ) - Telechelic oligomers by halogen atom transfer radical addition - TETRAHEDRON - n. volume 54 - pp. da 7849 a 7856 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Monodispersed telechelic oligomers have been efficiently prepared by Fe-0-FeCl3 promoted halogen atom transfer radical of functional telogens and taxogens, (C) 1998 Elsevier Science Ltd. All rights reserved.

M.R. Cramarossa; L. Forti; F. Ghelfi ( 1997 ) - Acetals by AlFe-pillared montmorillonite catalysis - TETRAHEDRON - n. volume 53 - pp. da 15889 a 15894 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

AlFe-pillared montmorillonite is an efficient catalyst for acetals preparation in CH2Cl2 at room temperature

L. Forti; F. Ghelfi; U.M. Pagnoni ( 1997 ) - Ferrocene promoted addition of methyl 2,2-dichloro-carboxylates to 1-alkenes - TETRAHEDRON - n. volume 53 - pp. da 4419 a 4426 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The Kharasch addition of methyl 2,2-dichlorocarboxylates to 1-alkenes is promoted by ferrocene in DMF at 100 degrees C, affording 1:1 adducts in satisfactory yields.

L. Forti; F. Ghelfi; E. Libertini; U.M. Pagnoni; E. Soragni ( 1997 ) - Halogen atom transfer radical addition of alpha-polychloroesters to olefins promoted by Fe-0 filings - TETRAHEDRON - n. volume 53 - pp. da 17761 a 17768 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The Kharasch addition of methyl 2,2-dichlorocarboxylates or trichloro acetic acid derivatives to alkenes, affording the corresponding 1:1 adducts, is promoted by the iron filings/N,N-dimethylformamide system.

M. Benedetti; L. Forti; F. Ghelfi; U.M. Pagnoni; R. Ronzoni ( 1997 ) - Halogen atom transfer radical cyclization of N-allyl-N-benzyl-2,2-dihaloamides to 2-pyrrolidinones, promoted by Fe-0-FeCl3 or CuCl-TMEDA - TETRAHEDRON - n. volume 53 - pp. da 14031 a 14042 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The halogen atom transfer radical cyclization of a N-allyl-N-benzyl-2,2-dihaloamides to 2-pyrrolidinones has been carried out in high yields under mild conditions, in a reaction promoted by CuCl-TMEDA or Fe-0-FeCl3 in acetonitrile or N,N-dimethylformamide, respectively.

F. Bellesia; L. Forti; F. Ghelfi; U.M. Pagnoni ( 1997 ) - The Fe-0 promoted addition of CCl4 and CCl3Br to olefins - SYNTHETIC COMMUNICATIONS - n. volume 27 - pp. da 961 a 971 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The radical addition of CCl4 or CCl3Br to olefins is efficiently promoted by iron filings in N,N-dimethylformamide under mild conditions.

Gabbi C; Ghelfi F; Grandi R ( 1997 ) - The preparation of beta-hydroxysulfoxides - SYNTHETIC COMMUNICATIONS - n. volume 27 - pp. da 2857 a 2863 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Oxidation of beta-hydroxy thioethers with MnO2-aqu.35%/HCl in methanol gives beta-hydroxy sulfoxides in high yields.

L. Antolini; F. Bellesia; F. Ghelfi; UM Pagnoni; A. Pinetti ( 1997 ) - The reaction of the acetates of alpha-chloro methyl hemiacetals with nucleophiles. Synthesis of 2-hydroxy-1,4-dithianes - GAZZETTA CHIMICA ITALIANA - n. volume 127 - pp. da 11 a 17 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The acetates of the methyl hemiacetals of alpha-halo aldehydes, 1, easily undergo nucleophilic attack by lithium thiolates or ethane dithiolate affording alpha-thioalkyl aldehydes 2 or 2-hydroxy-1,4-dithianes 3, respectively. 3-monosubstituted dithianes 3 smoothly dehydrate to 2,3-dihydro-1,4-dithiines 4, whereas 3,3-disubstituted derivatives give dimers 6. The single-crystal X-ray analysis of 6b shows that it crystallises in a racemic form, with the dithiane ring in a chair conformation and the exocyclic S(3) atom axially bonded to the ring. The crystal packing appears to be determined mainly by a weak C-H ... O hydrogen bonding interaction.

L. Forti; F. Ghelfi; U.M. Pagnoni ( 1996 ) - Fe-0 initiated halogen atom transfer radical addition of methyl 2-Br-2-Cl-carboxylates to olefins - TETRAHEDRON LETTERS - n. volume 37 - pp. da 2077 a 2078 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The halogen atom transfer radical addition (HATRA) of methyl 2-Br-2-Cl-carboxylates to alkenes is obtained in good yields by catalytic amounts of iron filings in dimethylformamide/1,2-dichloroethane at 80 degrees C under argon.

L. Forti; F. Ghelfi; R. Grandi; E. Libertini; U.M. Pagnoni ( 1996 ) - N-(2-hydroxyalkyl)-2,2-dihaloamides by amino-de-alkoxylation of methyl 2,2-dihalocarboxylates - SYNTHETIC COMMUNICATIONS - n. volume 26 - pp. da 3517 a 3526 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The chemoselective N-acylation of 2-amino alcohols with methyl 2,2-dichloro carboxylates occurs smoothly and in excellent yields.

L. Forti; F. Ghelfi; M. Lodi Lancellotti; U.M. Pagnoni ( 1996 ) - The CuBr/Fe-0 promoted radical addition of methyl 2-Br-2-Cl-carboxylates to olefins - SYNTHETIC COMMUNICATIONS - n. volume 26 - pp. da 1699 a 1710 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methyl 2-Br-2-Cl-carboxylates afford 2-alkyl-2-Cl-4-Br-carboxylates in fair yields by reaction with terminal alkenes, under mild conditions, through a radical process promoted by CuBr/Fe-0 in DMF/CH2Cl2

M. Benincasa; L. Forti; F. Ghelfi; E. Libertini; U.M. Pagnoni ( 1996 ) - Zinc promoted addition of methyl 2,2-dihalocarboxylates to carbonyl compounds - SYNTHETIC COMMUNICATIONS - n. volume 26 - pp. da 4113 a 4122 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methyl 2,2-dihalocarboxylates add easily to carbonyl compounds in fair to good yields through the intermediate formation of 2-haloester enolates; the reaction is promoted by zinc, following a ''Barbier'' type procedure.

L. Forti; F. Ghelfi; F. Munari; U.M. Pagnoni ( 1995 ) - Amino-de-Alkoxylation of Methyl 2,2-Dihalocarboxylates - TETRAHEDRON - n. volume 51 - pp. da 12285 a 12292 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

N-alkyl-2,2-dihaloamides were efficiently prepared by amino-de-alkoxylation of methyl 2,2-dihalocarboxylates, at room temperature without solvents and promoters. Excellent yields of anilides were obtained after addition of AlCl3.

M. BENINCASA; M. BONI; F. GHELFI; UM PAGNONI ( 1995 ) - Deprotection of α -halo aldehydes dimethyl acetals with acetic anhydride-acetyl chloride-sodium acetate trihydrate - SYNTHETIC COMMUNICATIONS - n. volume 25 - pp. da 1843 a 1848 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alpha-halo aldehydes are regenerated in excellent yields from the corresponding dimethyl acetals by acetic anhydride-acetyl chloride-sodium acetatetrihydrate in chloroform.

Bellesia F; Ghelfi F; Pagnoni UM; Pinetti A ( 1995 ) - gamma-Alkylketene dithioacetals from 2,3-dichloroaldehyde dithioacetals - GAZZETTA CHIMICA ITALIANA - n. volume 125 - pp. da 501 a 504 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The preparation of 2,3-dichloroaldehyde dithioacetals and their conversion to ketene dithioacetals by base are reported.

B. HAPP; T. BARTIK; C. ZUCCHI; MC ROSSI; F. GHELFI; G. PALYI; G. VARADI; G. SZALONTAI; IT HORVATH; A. CHIESIVILLA; C. GUASTINI ( 1995 ) - On the reactivity of acetylenes coordinated to cobalt, 9. Effects of substitution and coordination on the 13C-NMR chemical shifts of the sp carbons of (R1C2R2)Co2(CO)6 complexes. Molecular structure of (mu2-PhC2SiPh3)Co2(CO)6 - ORGANOMETALLICS - n. volume 14 - pp. da 809 a 819 ISSN: 0276-7333 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Thirty-four (mu(2)-R(1)C(2)R(2))Co-2(CO)(6) complexes (14 new) were prepared and characterized by their IR v(CO) and H-1- and C-13-NMR spectra. The C-13-NMR chemical shifts of the coordinated sp carbon atoms were correlated with those of the corresponding free acetylenes. This indicated that the interaction between the R(1) and R(2) groups and the C2Co2(CO)(6) moiety is very sensitive not only to the donor/acceptor character of R(1) and R(2) but also to the orbital symmetry of the atoms attached directly to the C(sp) atoms. The changes of the delta(C-13) values of the C(sp) atoms upon coordination were also analyzed in these terms. It is concluded that although the dinuclear mu(2)-coordination of the acetylene results in a high degree of excitation the stability of the C2Co2(CO)(6) moiety diminished the reactivity of the organic ligand. Differences in the reactivity of the (mu(2)-R(1)C(2)R(2))Co-2(CO)(6) complexes in carbonylation are also discussed. The crystal and molecular structure of (PhC(2)SiPh(3))Co-2(CO)(6) was determined by single crystal X-ray diffraction. This compound crystallizes in the orthorhombic Pbca space group with a = 28.790(2) Angstrom, b = 11.577(1) Angstrom, c = 17.833(2) Angstrom, Z = 8. The structure was determined with R = 0.039, R(w) = 0.036.

BENINCASA M; GRANDI R; GHELFI F; PAGNONI UM ( 1995 ) - OXIDATION OF ALPHA-ACETOXY ACETALS WITH TRICHLOROISOCYANURIC ACID - SYNTHETIC COMMUNICATIONS - n. volume 25 - pp. da 3463 a 3470 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

alpha-Acetoxy acid methyl esters are prepared in excellent yields by treating aliphatic alpha-acetoxy dimethyl acetals with trichloroisocyanuric acid in DMF.

M. Benincasa; L. Forti; F. Ghelfi; U.M. Pagnoni ( 1995 ) - Reductive homo-coupling of methyl 2-Br-2-Cl-carboxylates promoted by CuBr-Fe0 - TETRAHEDRON LETTERS - n. volume 36 - pp. da 1103 a 1106 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Dimethyl 2,3-dialkyl-2,3-dichloro-butanedioates are efficiently prepared in dimethylformamide or dimethylsulphoxide, through reductive homo-coupling of methyl 2-bromo-2-chlorocarboxylates promoted by CuBr-Fe-0.

GHELFI F; GRANDI R; PAGNONI UM ( 1995 ) - REGIOSPECIFIC CONVERSION OF ALPHA,BETA-EPOXY ACETATES TO 3-CHLORO-2-HYDROXY ACETATES - GAZZETTA CHIMICA ITALIANA - n. volume 125 - pp. da 215 a 217 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

3-chloro-2-hydroxy acetates are easily obtained by treating alpha,beta-epoxy acetates with chlorotrimethylsilane-dimethyl sulphoxide in acetonitrile.

L. Forti; F. Ghelfi; U.M. Pagnoni ( 1995 ) - Stereoselective Dehydrobromination of alkyl alpha-Br-alpha-Cl-carboxylates - TETRAHEDRON LETTERS - n. volume 36 - pp. da 3023 a 3026 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

(Z)-Alkyl alpha-Cl-alpha,beta-unsaturated esters are prepared in excellent yields by stereoselective dehydrobromination of alkyl alpha-Br-alpha-Cl-carboxylates with LiCl-Li2CO3 in dimethylformamide.

L. Forti; F. Ghelfi; U.M. Pagnoni ( 1995 ) - The CuBr/Fe promoted olefin alkylation of 2-Br-2-Cl-carboxylate methyl esters - TETRAHEDRON LETTERS - n. volume 36 - pp. da 2509 a 2510 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methyl 2-Br-2-Cl-carboxylates react with 1-octene in DMF/CH2Cl2 in a radical process promoted by CuBr/Fe, yielding 2-alkyl-2-Cl-4-Br-carboxylates smoothly and efficiently.

M. Boni; L. Forti; F. Ghelfi; U.M. Pagnoni ( 1994 ) - An efficient procedure to alfa-hydroxyaldehyde dimethyl acetals - TETRAHEDRON - n. volume 50 - pp. da 7897 a 7902 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alpha-Hydroxyaldehyde dimethyl acetals are prepared efficiently by conversion of alpha-haloaldehyde dimethyl acetals into alpha-haloaldehyde hemiacetal acetates and subsequent methanolysis promoted by lithium methoxide.

BELLESIA F; BONI M; GHELFI F; PAGNONI UM ( 1994 ) - METHYL ALPHA,ALPHA-DICHLORO-ESTERS BY OXIDATION-CHLORINATION OF CYCLIC ACETALS WITH TRICHLOROISOCYANURIC ACID - TETRAHEDRON LETTERS - n. volume 35 - pp. da 2961 a 2964 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methyl alpha-chloro- or alpha,alpha-dichloro-esters are obtained in excellent yields by oxidation chlorination of 2-alkyl-4,5-dimethyl-1,3-dioxolanes with trichloroisocyanuric acid.

A. VIZIOROSZ; R. UGO; R. PSARO; A. SIRONI; M. MORET; C. ZUCCHI; F. GHELFI; G. PALYI ( 1994 ) - Models of rhodium complexes bound to silica: preparation, structure and interconversion of dinuclear silyloxyrhodium complexes - INORGANIC CHEMISTRY - n. volume 33 - pp. da 4600 a 4603 ISSN: 0020-1669 [Articolo in rivista (262) - Articolo su rivista]
Abstract

(μ-Ph3SiO)2Rh2(COD)2 (2; COD = 1,5-cyclooctadiene) and (μ2-Ph3SiO)2Rh2(CO)4 (4) were prepd. by bridging ion metathesis and interconverted by terminal ligand exchange reactions. (μ2-Me3SiO)2Rh2(COD)2 was obtained alternatively by silylation of the bridging coordinated OH groups in (μ2-OH)2Rh2(COD)2 by N,N-bis(trimethylsilyl)-trifluoroacetamide. The crystal and mol. structure of 2 and 4 (R = Ph) derivs. was detd. by x-ray diffraction. Both complexes show a double square planar roof-like structure with roof angle ω = 109.6° (2) and 126.5° (4).

BONI M; GHELFI F; PAGNONI UM; ZUCCHI C ( 1994 ) - PREPARATION OF 2,2-DIHALOCARBOXYLIC ACID METHYL-ESTERS BY OXIDATION CHLORINATION OF 2-(1-HALOALKYL)-4-METHYL-1,3-DIOXOLANES WITH TRICHLOROISOCYANURIC ACID - BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN - n. volume 67 - pp. da 1622 a 1626 ISSN: 0009-2673 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Methyl 2,2-dichloro or 2-bromo-2-chloro carboxylates were obtained in excellent yields by oxidation-chlorination of 2-(1-haloalkyl)-4-methyl-1,3-dioxolanes with trichloroisocyanuric acid.

BONI M; GHELFI F; PAGNONI UM; ZUCCHI C ( 1994 ) - REDUCTIVE COUPLING OF METHYL ALPHA-BROMO-ALPHA-CHLOROCARBOXYLATES - TETRAHEDRON LETTERS - n. volume 35 - pp. da 7263 a 7266 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

CuBr-LiOCH3 in methanol efficiently promotes the reductive coupling of methyl alpha-bromo-alpha-chlorocarboxylates to dimethyl alpha,alpha'-dichloro-succinates.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1994 ) - REGIOSPECIFIC HYDROGEN-CHLORIDE ELIMINATION FROM ALPHA,BETA-DICHLOROALKYL PHENYL SULFIDES - GAZZETTA CHIMICA ITALIANA - n. volume 124 - pp. da 337 a 339 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

alpha,beta-Dichloroalkyl phenyl sulphides undergo regiospecific hydrogen chloride eliminations to afford alpha- or beta-chloro-1-alkenyl phenyl sulphides in good yields.

FABRETTI A; GHELFI F; GRANDI R; PAGNONI UM ( 1994 ) - SULFOXIDES FROM THIOETHERS AND MNO2-HCL - SYNTHETIC COMMUNICATIONS - n. volume 24 - pp. da 2393 a 2398 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Treatment of thioethers with manganese(IV)oxide-35% aqueous hydrogen chloride in methanol gives sulfoxides in high yields; sulfones are not produced

F. BELLESIA; M. BONI; F. GHELFI; U. M. PAGNONI ( 1994 ) - SYNTHESIS OF 2-(1-CHLOROALKYL)-1,3-BENZODITHIOLES AND 2-ALKYLIDENE-1,3-BENZODITHIOLES - JOURNAL OF HETEROCYCLIC CHEMISTRY - n. volume 31 - pp. da 1721 a 1723 ISSN: 0022-152X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Boron trifluoride promoted transdithioacetalization of alpha-chloroacetals with 1,2-benzodithiol affords good yields of 2-(1-chloroalkyl)1-3-benzodithioles, which dehydrochlorinates very satisfactorily to the corresponding 2-alkylidene-1,3-benzodithioles.

BONI M; GHELFI F; PAGNONI UM; PINETTI A ( 1994 ) - TRICHLOROISOCYANURIC ACID OXIDATION OF 2-CHLORO ALDEHYDE ACETALS TO 2-CHLORO ACID-ESTERS - BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN - n. volume 67 - pp. da 156 a 159 ISSN: 0009-2673 [Articolo in rivista (262) - Articolo su rivista]
Abstract

2-Chloro acid methyl esters were prepared in good yields treating 2-chloro aldehyde dimethyl acetals with trichloroisocyanuric acid in DMF. Aldehyde dimethyl acetals with the 2-halogen on a tertiary carbon atom were poorly reactive and could be oxidized effeciently only after their transformation into 1,3-dioxolanes.

F. Bellesia; M. Boni; F. Ghelfi; U.M. Pagnoni. ( 1993 ) - Alfa-Chloromercaptals from alfa-Chloroacetals and Thiols - TETRAHEDRON - n. volume 49 - pp. da 199 a 206 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

alfa-Chloromercaptals are prepared in good yields by a CoCl2-trimethylchlorosilane catalized transdithioacetalization of alfa-chloroacetals with tiols in acetonitrile.

BELLESIA F; BONI M; GHELFI F; PAGNONI UM ( 1993 ) - ALPHA-CHLOROMERCAPTALS FROM ALPHA-CHLOROACETALS AND THIOLS - TETRAHEDRON - n. volume 49 - pp. da 199 a 206 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alpha-chloromercaptals are prepared in good yields by a CoCl2-trimethylchlorosilane catalysed transdithioacetalization of alpha-chloroacetals with thiols in acetonitrile.

GHELFI F; GRANDI R; PAGNONI UM ( 1993 ) - CARBONYL REGENERATION FROM OXIMES AND SEMICARBAZONES BY TRIMETHYLCHLOROSILANE-DIMETHYLSULFOXIDE - SYNTHETIC COMMUNICATIONS - n. volume 23 - pp. da 2279 a 2284 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Treatment of oximes and semicarbazones of saturated and (alpha,beta-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions.

BELLESIA F; BONI M; F. GHELFI; PAGNONI U. M ( 1993 ) - DIMETHYLACETALS BROMINATION BY Br2-TRIMETHYLCHLOROSILANE-NaBr (Bardi editore Societa Chimica Italiana:Viale Liegi 48, 00198 Rome Italy:011 39 06 8549691, EMAIL: soc.chim.it@agora.stm.it, Fax: 011 39 06 8548734 ) - GAZZETTA CHIMICA ITALIANA - n. volume 123 - pp. da 629 a 629 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

α-Bromo di-Me acetals are obtained in excellent yields by treating di-Me acetals with Br2-NaBr-chlorotrimethylsilane in CH3OH/CH3CN (2:1). The method is suitable for large scale prepn.

BELLESIA F; BONI M; GHELFI F; PAGNONI UM ( 1993 ) - KETENE THIOACETALS FROM ALPHA-CHLOROMERCAPTALS - SYNTHETIC COMMUNICATIONS - n. volume 23 - pp. da 3179 a 3184 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Excellent yields of ketene thioacetals are obtained from 2-(1-chloroalkyl)-1,3-dithiolanes or 2-(1-chloroalkyl)-1,3-dithianes.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1993 ) - OXIDATION OF THIOETHERS BY MANGANESE(IV) OXIDE-TRIMETHYLCHLOROSILANE - SYNTHETIC COMMUNICATIONS - n. volume 23 - pp. da 1759 a 1769 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Thioethers are transformed by manganese(IV) oxide-trimethylchlorosilane in CH3OH in high yields to sulphoxides, exclusively.

BONI M; GHELFI F; PAGNONI UM; PINETTI A ( 1993 ) - REGENERATION OF ALPHA-HALOALDEHYDES FROM ALPHA-HALODIMETHYLACETALS - SYNTHETIC COMMUNICATIONS - n. volume 23 - pp. da 1915 a 1921 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alpha-Chlorodimethylacetals are hydrolysed in a mixture of acetic acid and aq. HCI (3.5 M) to alpha-chloroaldehydes in excellent yields. On replacing HCI by HBr the same procedure is applied to alpha-bromodimethylacetals.

M. Bressan; L. Forti; F. Ghelfi; A. Morvillo ( 1993 ) - Ruthenium(II)-catalyzed oxidation of alcohols by persulfate - JOURNAL OF MOLECULAR CATALYSIS - n. volume 79 - pp. da 85 a 93 ISSN: 0304-5102 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Alcohols are oxidized to carbonylic compounds by aqueous persulfate in the presence of catalytic amounts (0.2%) of ruthenium trichloride and of a choice of ruthenium(II) complexes. Secondary alcohols are quantitatively converted to ketones, whereas primary alcohols can be converted to aldehydes with good selectivities. A kinetic investigation suggests a concerted mechanism for the bi-electronic oxygen transfer.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1993 ) - THE REACTION OF ALKYL PHENYL SULFIDES WITH MANGANESE-DIOXIDE AND ACETYL-CHLORIDE - GAZZETTA CHIMICA ITALIANA - n. volume 123 - pp. da 289 a 291 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In a one-pot reaction, manganese dioxide in stoicheiometric amounts and acetyl chloride transform alkyl phenyl sulphides into the corresponding 1-alkenyl phenyl sulphides; these latter products can undergo chlorination of the double bond promoted by the excess manganese dioxide.

BELLESIA F; GHELFI F; GRANDI R; PAGNONI UM; PINETTI A ( 1993 ) - THE REACTION OF PYRROLES WITH TRIMETHYLHALOSILANES-DIALKYL SULFOXIDES - JOURNAL OF HETEROCYCLIC CHEMISTRY - n. volume 30 - pp. da 617 a 621 ISSN: 0022-152X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Pyrroles are powerful nucleophiles in the reaction with dialkyl sulfoxides and trimethylchlorosilane (TMCS) or trimethylbromosilane (TMBS), affording sulfonium salts or halo derivatives, generally in good yields.

BELLESIA F; BONI M; GHELFI F; GRANDI R; PAGNONI UM; PINETTI A ( 1992 ) - ACETAL CHLORINATION WITH MNO2-TRIMETHYLCHLOROSILANE - TETRAHEDRON - n. volume 48 - pp. da 4579 a 4586 ISSN: 0040-4020 [Articolo in rivista (262) - Articolo su rivista]
Abstract

alpha-Chloroacetals am obtained in almost quantitative yields, by treating acetals with MnO2-trimethylchlorosilane in CH3OH:CH3CN (1:1). The halogenation is explained by a ligand-transfer process on an enolether intermediate, mediated by a Mn(IV)-chloride species.

BELLESIA F; BONI M; GHELFI F; PAGNONI UM; PINETTI A ( 1992 ) - BETA-CHLOROALKYL SULFIDES FROM ME2S/SO2CL2/ME2SO AND ALKENES - SYNTHETIC COMMUNICATIONS - n. volume 22 - pp. da 1101 a 1108 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A novel method to prepare beta-chloroalkyl sulfides from alkenes and Me2S-SO2Cl2-Me2SO is described, methanesulfenyl chloride being suggested as intermediate.

GHELFI F; GRANDI R; PAGNONI UM ( 1992 ) - CARBONYL REGENERATION FROM PARA-TOLUENSULFONHYLHYDRAZONES BY TRIMETHYLCHLOROSILANE-DIMETHYLSULFOXIDE - SYNTHETIC COMMUNICATIONS - n. volume 22 - pp. da 1845 a 1850 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Treatment of p-tosylhydrazones of saturated and alpha,beta-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1992 ) - THE REACTION OF BENZYLIC ALCOHOLS WITH CHLOROTRIMETHYLSILANE/DIMETHYL SULFOXIDE - GAZZETTA CHIMICA ITALIANA - n. volume 122 - pp. da 437 a 439 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

With catalytic amounts of chlorotrimethylsilane/dimethyl sulphoxide (CTMSO/DMSO) in acetonitrile benzylic alcohols have been found to give high yields of styrenes. By using stoicheiometric amounts of reagents, different reaction pathways are observed: an elimination-addition sequence occurs with secondary and tertiary alcohols affording vicinal dichloro derivatives, beta-chloro thioethers and allyl chlorides, whereas a nucleophilic substitution to the corresponding monochlorides occurs star-ting from primary and sterically hindered substrates.

F. Bellesia; F. Ghelfi; U. M. Pagnoni; A. Pinetti ( 1991 ) - Chlorination of alkenes with manganese dioxide-manganese dichloride-acetyl chloride in dimethylformamide - SYNTHETIC COMMUNICATIONS - n. volume 21 - pp. da 489 a 494 ISSN: 0039-7911 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Manganese(IV)ossido, MnCl2, acetil cloruro, N,N-dimetilformamide,alcheni, clorurazione

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1991 ) - ON THE INTERMEDIATES OF THE REACTION OF KETONES WITH MNO2-CHLOROTRIMETHYLSILANE - GAZZETTA CHIMICA ITALIANA - n. volume 121 - pp. da 245 a 247 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The chlorination of ketones with MnO2-chlorotrimethylsilane occurs through an enolization catalyzed by an Mn(IV) species, which is also involved in the halogenation of alkenes.

SISAK A; SIRONI A; MORET M; ZUCCHI C; GHELFI F; PALYI G ( 1991 ) - O-SILYLATION OF ACYLCOBALT TETRACARBONYLS - SYNTHESIS OF A NEW TYPE OF DINUCLEAR MU-2-HYDROXYCARBENE COBALT CARBONYL DERIVATIVES - JOURNAL OF THE CHEMICAL SOCIETY, CHEMICAL COMMUNICATIONS - n. volume - - pp. da 176 a 178 ISSN: 0022-4936 [Articolo in rivista (262) - Articolo su rivista]
Abstract

O-Silylation of acylcobalt tetracarbonyls, RC(O)Co(CO)4, gives the dinuclear carbene complexes [{mu-2-RC(OSiR'3)}(mu-2-CO)Co2(CO)6], of which one derivative (R = Me, R' = Ph) was characterized by X-ray diffraction.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1991 ) - REACTION OF MANGANESE(III) ACETATE-ACETYL CHLORIDE WITH BENZENES - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume - - pp. da 284 a 285 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Manganese(III) acetate-acetyl chloride smoothly halogenates benzenes at the aromatic nucleus while benzylic chlorination is observed on substrates bearing an electron-donor substituent and an ortho or para methyl group; the results are rationalized by a reaction pathway involving a single electron transfer from the substrate to a manganese(III) species.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1991 ) - THE REACTION OF STYRENES WITH CHLOROTRIMETHYLSILANE DIMETHYL-SULFOXIDE - GAZZETTA CHIMICA ITALIANA - n. volume 121 - pp. da 559 a 561 ISSN: 0016-5603 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The chlorotrimethylsilane-dimethyl sulphoxide reagent system gives rise to smooth and high yield transformations of: i) beta-alkyl- and beta,beta-dialkyl-styrenes into vicinal dichlorides, ii) alpha,beta-dialkyl- and alpha,beta,beta-trialkyl-styrenes into allyl chlorides.

BELLESIA F; F. GHELFI; PAGNONI U. M; PINETTI A ( 1990 ) - PHOTO-OXIDATION OF METHYL LINOLEATE AND THE EFFECT OF ALFA-TOCOPHEROL, ASORBIC ACID BETA-CAROTENE AND HEAVY METAL IONS ( - ADVANCES IN FREE RADICALS IN DISEASE II ) (CLEUP PADOVA ITA ) - pp. da 59 a 63 ISBN: 8871783425 [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The effect of antioxidant vitamins A, C and E on the photo-oxidation of methyl linoleate was studied.

F. Bellesia; F. Ghelfi; U. M. Pagnoni; A. Pinetti ( 1990 ) - The chlorination of ketones with manganese(IV) chloride - JOURNAL OF CHEMICAL RESEARCH - n. volume - - pp. da 188 a 189 ISSN: 0308-2350 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In situ formation of MnCl4 by reaction of MnO2 with ClSiMe3 or AcCl followed by reaction with a ketone gives the α-chloro ketone. A CH2 group is attacked in preference to a Me group; steric factors limit the chlorination of CH groups.

F. Bellesia; F. Ghelfi; U.M. Pagnoni; a. Pinetti ( 1989 ) - Chlorination of Alkenes with Manganese Dioxide-Trimethylchlorosilane - JOURNAL OF CHEMICAL RESEARCH - n. volume S - pp. da 108 a 109 ISSN: 0308-2350 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title reagent system (MnO2-TMCS) give rise to a smooth and high-yeld chlorinationof unconiugated alkenes without isomerization occurring. The trans vic-dichloro derivatives are obtained from cyclic substrates with high stereoselectivity.

BELLESIA F; GHELFI F; PAGNONI UM; PINETTI A ( 1989 ) - DIENE CHLORINATION WITH MANGANESE-DIOXIDE TRIMETHYL-CHLOROSILANE - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume - - pp. da 360 a 361 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Reaction of dienes, e.g. H2C:CH(CH2)nCH:CH2 (n = 2-4), Me2C:CHCH2CH2CMe:CHCH2OAc, 1,5- and 1,4-cyclooctadiene, and 4-vinylcyclohexenes, with the title reagents resulted in chlorination of the more highly substituted double bond.

F. Bellesia; F. Ghelfi; U. M. Pagnoni; A. Pinetti ( 1989 ) - The treatment of indoles with trimethylhalogenosilanes and sulphoxides J. Chem. Res. (S) 1989, 182 - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 182 a 183 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Indole derivs. I (R = H, Me; R1 = H, Me, Ph; R2 = H) were treated with DMSO and Me3SiCl to give I (same R, R1; R2 = S+Me2 Cl-). Treatment of I with Me3SiCl and Et2S(O) gave mainly I (same R, R1; R2 = Cl). No sulfonium compds. were formed when I (R = R2 = H; R1 = H, Me) were treated with Me3SiCl and Bu2S(O) or with Me3SiBr and DMSO. Treatment of I (R = H, R1 = R2 = Me) with Me3SiCl and DMSO gave 56% I (R = H, R1 = Me, R2 = CHO). The formation of different electrophilic S or Cl species is given as an explanation for product formation.

F. Ghelfi; G. Romano; U. M. Pagnoni ( 1988 ) - Facile conversion of α,β-epoxy ketones to 2-chloro-3-hydroxy ketones by trimethylchlorosilane-dimethyl sulfoxide (Scientific Reviews Limited:41/43 Green Lane, Northwood, Middlesex HA6 3AE United Kingdom ) - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 200 a 201 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Title cleavage of epoxy ketones proceeded stereo- and regiospecifically to give 2-chloro-3-hydroxy ketones. Aryl epoxides afforded the isomeric 2-hydroxy-3-chloro ketones. Thus, treatment of epoxide I with Me3SiCl-Me2SO in MeCN at room temp. afforded 96% chlorohydrin HOCMe2CHClCOMe.

BELLESIA F; F. GHELFI; PAGNONI U. M; PINETTI A ( 1987 ) - THE REACTION OF THRICHLORO AND TRIMETHYLBROMOSILANE-DIMETHYLSULFOXIDE REAGENT SYSTEM ON ALKENES (Scientific Reviews Limited:41/43 Green Lane, Northwood, Middlesex HA6 3AE United Kingdom ) - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 238 a 239 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Me3SiCl-DMSO combine to form a reagent which transforms alkenes (e.g., BuCMe:CH2, 1-methylcyclohepxene, norbornene) into 2-chloroalkyl Me sulfides [e.g., BuCMeClCH2SMe, 1-chloro-1-methyl-2-(methylthio)cyclohexane, chloro(methylthio)norbornane I] regio- and stereoselectively.

BELLESIA F; F. GHELFI; PAGNONI U. M ( 1987 ) - TRIMETHYLCHLOROSILANE-MEDIATED FORMATION OF 2-CHLOROCYCLOHEXYL SULPHIDES BY SULPHOXIDES (Scientific Reviews Limited:41/43 Green Lane, Northwood, Middlesex HA6 3AE United Kingdom ) - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 24 a 24 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The title 2-chlorocyclohexyl sulfides, e.g. I (R = Me, Et, Me2CH, Bu) were prepd. by treating cyclohexene with the corresponding alkyl sulfoxides RSOR in the presence of Me3SiCl. Unsym. sulfoxides, e.g. EtSOBu gave a mixt. of products I (R = Et, Bu). Tetramethylene sulfoxide (II) gave aldehyde I (R = CH2CH2CH2CHO) as the major product. A mechanism is presented in which 2 mol. of sulfoxide form an intermediates S-alkoxysulfonium salt.

BELLESIA F; F. GHELFI; GRANDI R; PAGNONI U. M ( 1986 ) - REACTIONS OF THE TRIMETHYLCHLOROSILANE-DIMETHYL SULPHOXIDE REAGENT WITH CARBONYL COMPOUNDS (Scientific Reviews Limited:41/43 Green Lane, Northwood, Middlesex HA6 3AE United Kingdom ) - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 426 a 427 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The Me3SiCl-Me2SO system is an efficient reagent for the smooth chlorination of unconjugated carbonyl compds. at the more substituted α-carbon atom. β-Dicarbonyl substrates are transformed into α-chloro-α-thiomethyl ether derivs.

F. Bellesia; F. Ghelfi; R. Grandi; U.M. Pagnoni ( 1986 ) - Regioselective alfa-Bromination of Carbonyl Compounds with Trimethylbromosilane-Dimethyl Sulphoxide - JOURNAL OF CHEMICAL RESEARCH - n. volume s - pp. da 428 a 429 ISSN: 0308-2350 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Trimethylbromosilane-Dimethyl Sulphoxide (TMBS-DMSO) reagent system brominates efficiently and regiospecifically at the more alkyl-substituted alfa-position of carbonyl compounds

F. Bellesia; F. Ghelfi; U.M. Pagnoni; A. Pinetti ( 1986 ) - The Base-Catalyzed Cyclization of 10-Oxocitral Synthesis of Chrysomelidial and Dehydroiridodial - TETRAHEDRON LETTERS - n. volume 27 - pp. da 381 a 382 ISSN: 0040-4039 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Base treatment of 10-oxocitral gives chrysomelidial and dehydroiridodial, supporting its intermediacy in the biosynthesis of some iridoid glucosides.

F. Bellesia; F. Ghelfi; R. Grandi; U. M. Pagnoni ( 1985 ) - Base-promoted rearrangement of 2,3-epoxycyclohexanones to phenols - JOURNAL OF CHEMICAL RESEARCH. SYNOPSES - n. volume / - pp. da 400 a 401 ISSN: 0308-2342 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The reactions were examd. of ten 2,3-epoxycyclohexanones with NaH in (MeOCH2)2; the products were trapped by treatment with Me3CSiMe2Cl and Et3N. Generally, the main reaction products were the corresponding silylated phenols. E.g., carvone epoxide gave 66% 3,4-Me3CSiMe2O(Me)C6H3CMe:CH2. This aromatization proceeds by deprotonation at the α'-C atom followed by O-silylation, β'-proton removal, olefinic bond shift, oxirane ring cleavage, and 1,2-elimination.