Preparation of acetates of glucosides of steroid and triterpene alcohols via the isomeric orthoesters

Abstract

The conversion of steroid and triterpene 1,2-orthoacetates of α-D-glucose into the isomeric glucosides and substances of nonglucosidic nature has been studied. Isomerization was carried out in nitromethane in the presence of 0.36 mmole of HgBr2 per mmole of orthoester. The yield of cholesterol β-glucoside tetraacetate under these conditions was 65.3%, of β-sitosterol β-glucoside tetraacetate 53.1%, of betulin 28-C-β-glucoside pentaacetate 59.8%, and of betulin β-diglucoside octaacetate 46.3%. It has been established that the initial stage of the conversion of cholesteryl orthoacetate of α-D-glucose in nitromethane in the presence of mercuric bromide is the partial hydrolysis of the orthoester with the formation of the alcohol, which participates in the subsequent transformation of the orthoester.