1: 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-glucopyranose; tri-O-acetyl-D-galactal With 1,2-diphenyl-1-keto-2,2-dimethoxyethane in ethanol; dichloromethane T=20°C; 1 h; UV-irradiation; 2: acetic anhydride With pyridine T=20°C; 2 h; optical yield given as percent deregioselective reaction;