ethyl 4-(1-benzyl-2-oxopyrrolidin-3-yl)-5-(diazo-1,3-dioxobutyl)pyrrole-2-carboxylate

1'-Benzyl-2-(2-chloro-acetyl)-2'-oxo-2',3',4',5'-tetrahydro-1H,1'H-[3,3']bipyrrolyl-5-carboxylic acid ethyl ester

ethyl 4-(1-benzyl-2-oxo-Δ3-pyrrolidin-3-yl)-5-(3-methylisoxazol-5-yl)pyrrole-2-carboxylate

ethyl 4-(1-benzyl-2-oxopyrrolidin-3-yl)-5-(3-amino-1-oxo-2-butenyl)pyrrole-2-carboxylate

ethyl 4-(1-benzyl-2-thioxopyrrolidin-3-yl)-5-(3-amino-1-oxobut-2-enyl)pyrrole-2-carboxylate