dimethyl (1S,2S,5R,6S)-2-acetamidobicyclo[3.1.0]hex-3-ene-2,6-dicarboxylate

(1S,2R,3S,4R,5R,6R)-dimethyl 2-acetamido-3,4-dihydroxybicyclo[3.1.0]hexane-2,6-dicarboxylate

(1R,1aR,1bR,4aS,5R,5aS)-5-Acetylamino-3-ethoxy-hexahydro-2,4-dioxa-cyclopropa[a]pentalene-1,5-dicarboxylic acid dimethyl ester

ethyl (1S,5R,6S)-2-oxobicyclo[3.1.0]hexane-6-carboxylate