Dithiols. Part XXIV. Proof of the epoxide chirality in 2,3-epoxypropyl β-D-glucopyranoside by correlation with (R)-2,3-thiocarbonyldithiopropanol

Abstract

Epoxidation of allyl 2,3,4,6-tetra-O-acetyl-β-D-glucoside is stereoselective and gives a 7 : 3 preponderance of the (R)-epoxide; this is proved by conversion into the (R)-trithiocarbonate, followed by hydrolysis to give (R)-2,3-(thiocarbonyldithio)propan-1-ol. Epoxidation of the α-anomer is only slightly stereoselective. Conversion of the glycosidic trithiocarbonate into the dithiocarbonate (carbonyl form), followed by solvolysis, provides a new synthesis of 2,3-dimercaptopropyl glucopyranoside.