Oxydations et halogénations régiosélectives et réactions carbéniques de dérivés de sucres portant un groupement thioéther

Abstract

Regioselective Oxidations, Regioselective Halogenations and Carbene Reactions of Sugar Derivatives Bearing a Thioether Group Regioselective stoechiometrically controlled procedures are described for the oxidation of thiosugars either at the sulfur atom (to sulfoxides or sulfones) or at a hydroxymethylene group (to ketosugars). Ruthenium tetraoxide reacted at both sites. Chloration (SO2Cl2) of β‐ketothioether sugar derivative 3 took place exclusively at C(6). Evidence is given that a chlorosulfonium intermediate C was formed when the dichloroketothiosugar derivative 6 was treated with SO2Cl2. The carbene generated from the tosylhydrazone 16 rearranged to the enoses 17–20, the migrating group coming in equal proportions from C(4) and C(6). Some stereochemical aspects of these reactions are discussed.