tert-butyl (2S,3S,4S)-4-((S)-1-(1,3-dioxolan-2-yl)ethyl)-3-(2-hydroxyethyl)-2-(hydroxymethyl)pyrrolidine-1-carboxylate

(2S,3S,4S)-1-tert-butyl 2-methyl 3-(2-methoxy-2-oxoethyl)-4-((R)-1-oxopropan-2-yl)pyrrolidine-1,2-dicarboxylate

(2S,3S,4S)-2-(tert-Butyl-dimethyl-silanyloxymethyl)-4-(1-[1,3]dioxolan-2-yl-ethyl)-3-(2-hydroxy-ethyl)-pyrrolidine-1-carboxylic acid tert-butyl ester

1-(tert-butyl) 2-methyl (2S,3S,4R)-3-(2-methoxy-2-oxoethyl)-4-(4-methoxybut-3-en-2-yl)pyrrolidine-1,2-dicarboxylate

1-(tert-butyl) 2-methyl (2S,3S,4S)-4-((S)-1-(1,3-dioxolan-2-yl)ethyl)-3-(2-methoxy-2-oxoethyl)pyrrolidine-1,2-dicarboxylate