Stereocontrolled Photoinduced Glycosylation Using an Aryl Thiourea as an Organo photoacid

Photoinduced glycosylation of alcohols with alpha-glucosyl trichloroacetimidates, using aryl urea and thioureas as organo photoacids, was examined under long wavelength UV (ultraviolet) irradiation. The results show, for the first time, that such glycosylations proceed effectively to give the corresponding glycosides in high yields. In addition, high beta-stereoselectivity was obtained under high concentration conditions, whereas high alpha-stereoselectivity was realized under low concentration conditions.