1: (2S,4R,5S)-4-O-t-butyldimethylsilyl-1,2-O-isopropylidene-1,2,4,5-tetrahydroxy-5-phenylpentan-3-one With periodic acid in ethyl acetate T=20°C; Oxidation; 2 h; 2: diazomethane in diethyl ether Methylation; 3: With hydrogen fluoride in acetonitrile T=20°C; Substitution; 6 h;