(-)-(1'R,4S,5'S,6'S)-2,5-dioxospiro(imidazolidine-4,4'-[2]-thiabicyclo[3.1.0]hexane)-6'-carboxylic acid 2',2'-dioxide

(1R,4S,5S,6S)-4-amino-2,2-dioxo-2λ6-thia-bicyclo[3.1.0]hexane-4,6-dicarboxylic acid dimethyl ester

4-amino-2-thia-bicyclo[3.1.0]hexane-4,6-dicarboxylic acid dimethyl ester

dimethyl (-)-(1R,4S,5S,6S)-4-(N-tert-butyloxycarbonylamino)-2-thiabicyclo[3.1.0]hexane-4,6-dicarboxylate

dimethyl (+)-(1R,2R,4S,5S,6S)-4-(N-tert-butyloxycarbonylamino)-2-thiabicyclo[3.1.0]hexane-4,6-dicarboxylate-2-oxide