Reactions of Silica Chloride (SiO₂Cl)/DMSO, a Heterogeneous System for the Facile Regeneration of Carbonyl Compounds from Thioacetals and Ring-Expansion Annelation of Cyclic Thioacetals

Abstract

Silica chloride (SiO(2)Cl)/DMSO, as a heterogeneous system, has been efficiently used for deprotection of thioacetals into aldehydes in dry CH(2)Cl(2) at room temperature. Thioketals without enolizable hydrogens adjacent to a sulfur atom are converted easily to the corresponding ketones in high yields under similar reaction conditions. However, thioketals with enolizable methyl and methylene groups undergo ring-expansion reactions to afford 1,4-dithiepins and 1,4-dithiins in dry CH(2)Cl(2) at room temperature in good yields.