Pierre Sarda

Reduction par le zinc en presence d'acides—I : Reduction des cetones α,β-ethyleniques avec formation de cyclopropanols☆

The reduction of 2-aryl or 3-alkyl cyclohex-2-en-ones 1, 9 and 22 and of arylidene cyclopentanones 2, 14, 16 and 19, by zinc and anhydrous HCl in ether in the presence of acetic anhydride, leads to a mixture of bicyclic cyclopropanol acetates and unrearranged saturated ketones.

Synthesis of C-2″β- and C-2″α-fluoro avermectin B1a

A synthesis of protected C-2β- and C-2α-fluoro oleandrosyl fluorides is presented; coupling of these carbohydrates with avermectin B1a monosaccharide 5-O-t-butyldimethylsilyl derivative, followed by deprotection, furnished the title compounds whose biological activity was evaluated.

Stereospecific Access to 2,3,4-Trideoxy-2-3-4-Trifluoro-d-Glucose and d-Galactose Derivatives

Abstract Fluorodehydroxylation of 1,6-anhydro-β-D-gluco- and galacto-pyranose derivatives was investigated on compounds having only one free hydroxy group. The reaction proceeded with complete retention and inversion of configuration at C-3 and C-4 respectively and allowed the stereospecificic preparation of 1, 6-anhydro-2, 3, 4-trideoxy-2,3,4-trifluoro-β-D-gluco- and galactopyranose. Acid catalyzed opening of their 1, 6-anhydro bridge gave the corresponding 1, 6-di-O-acetyl gluco- and galactopyranose derivatives.

Synthesis of α-azido aldehydes Stereoselective access to a protected lincosamine analogue

Abstract Reaction of ketone 3 with dichloromethyllithium gave a unique branched-chain dichloromethyl sugar 7 whose structure was ascertained by X-ray crystallography. Transformation of 7 in seven steps, involving the key-intermediate α-azido-aldehyde 9 , afforded the protected lincosamine analogue 14 .

The clemmensen reduction of enol ethers: cyclopropyl ethers from mono- and di-methoxycyclohexa-1,4-dienes

Abstract Clemmensen reduction (zinc and hydrogen chloride in dry diethyl ether) of 1-methoxy- and 1,5-dimethoxy-cyclohexa-1,4-diene affords the cyclopropyl ethers, 1-methoxy- and 1,5-dimethoxy-bicyclo[3.1.0]hexane; in the presence of acetic anhydride, reduction of 6-acetyl-1-methoxy-6-methyl-cyclohexa-1,4-diene leads regiospecifically to 7-acetoxy-1-methoxy-6,7-dimethyl-bicyclo[4.1.0]hept-4-ene.