(2S,3S,4S)-4-Acetyl-3-carboxymethyl-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester

(2S,3S,4R)-4-Acetyl-3-carboxymethyl-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester

(2S,3S,4S)-3-[2-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-2-(tert-butyl-dimethyl-silanyloxymethyl)-4-((Z)-1-formyl-buta-1,3-dienyl)-pyrrolidine-1-carboxylic acid tert-butyl ester