上游原料
cyclopentanone1-(tert-butyl) 2-ethyl (2S)-5-oxo-1,2-pyrrolidinedicarboxylate1-(tert-butyl) 2-ethyl (2S)-4-(1-hydroxycyclopentyl)-5-oxo-1,2-pyrrolidinedicarboxylate1-(tert-butyl) 2-ethyl (2S)-4-cyclopentylidene-5-oxo-1,2-pyrrolidinedicarboxylate(2S)-2-[(tert-butoxycarbonyl)amino]-4-cyclopentylidenepentanedioic acid
