SILICA GEL-CATALYZED ADDITION OF THIOPHENOL TO ALPHA-BETA-EPOXYSILANES AND EPOXIDES - SYNTHESIS OF ALPHA-HYDROXYALDEHYDE DERIVATES FROM ALPHA-BETA-EPOXYSILANES

(Trimethylsilyl)oxiranes react with thiophenol in the presence of sili ca gel to give regioselectively alpha-adducts. The adducts were transf ormed into the respective alpha-hydroxyaldehyde derivatives in a seque nce of reactions involving oxidation of sulfide to sulfoxide, sila-Pum merer rearrangement and hydrolysis of the acetal group. (Triphenylsily l)oxiranes in reaction with thiophenol and silica gel provide the resp ective alpha-adducts or a mixture of alpha and beta adducts. Represent ative all-carbon oxiranes react with thiophenol in the presence of sil ica gel to afford adducts in excellent yields.