4-ethyl 1-methyl [2S,2(1R)]-2-[2-(tert-butyldiphenylsilyl)oxy-1-[3-(methoxymethoxy)propionyl]oxyethyl]-3-diazo-2-hydroxybutanediote

(2S,3R)-4-(tert-Butyl-diphenyl-silanyloxy)-2-hydroxy-3-(3-methoxymethoxy-propionyloxy)-butyric acid methyl ester

methyl (R)-4-(tert-butyldiphenylsilyl)oxy-3-[3-(methoxymethoxy)propionyl]oxy-2-oxobutanoate

5-ethyl 4-methyl (1S,3R,4S,5R,6R,7S)-6,7-diacetyl-3-[(tert-butyldiphenylsilyl)oxymethyl]-1-[2-(methoxymethoxy)ethyl]-4-(trimethylsilyl)oxy-2,8-dioxabicyclo[3.2.1]octane-4,5-dicarboxylate

4-ethyl 1-methyl [2R,2(1R)]-2-[2-(tert-butyldiphenylsilyl)oxy-1-[3-(methoxymethoxy)propionyl]oxyethyl]-3-diazo-2-(trimethylsilyl)oxybutanedioate