Stereoselective Tandem Epoxidation-Alcoholysis/Hydrolysis of Glycals with Molybdenum Catalysts

Abstract

Molybdenum catalysts are efficient and selective catalysts for the tandem epoxidation/alcoholysis or epoxidation/hydrolysis of glucal and galactal derivatives. In glucal derivatives the selectivity is mainly controlled by the allylic substituent at position 3 of the glycal, obtaining in general the products derived from the initial formation of the α-epoxide (gluco) when this hydroxy group is protected, while products derived from the β-epoxide (manno) are mainly obtained when it is unprotected. In galactal derivatives the estereoselectivity is always high to give the α-epoxide (galacto) and independent of the protecting groups.