Efficient Chemoselective Mild Deprotection of S,Sand S,O-Acetals and Ketals with Electrophilic Halogens

Abstract

A novel and simple method for the chemoselective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs with electrophilic halogens to their corresponding carbonyl compounds is described using N-bromosuccinimide, N-chlorosuccinimide, 2,4,4,6-tetrabromo-2,5-cyclohexen-1-one, trichlorocyanuric acid, or molecular bromine in aqueous acetonitrile. The use of these reagents in the presence of hydrated silica gel provide efficient, novel, and mild procedures for the deprotection of cyclic and acyclic O,O-, S,S-, and S,O-acetals and ketals in excellent yields in short reaction times.

Kewords:

• Chemoselective
• deprotection
• electrophilic halogens
• hydrated silica gel
• S,O-acetals and ketals
• S,S-acetals and ketals

We are thankful to the Sistan and Baluchestan University Research Council for their partial support of this work