5원자 고리형 ${eta}$-keto ester와 phenylalkylamine의 탈수축합으로 얻은 enamine A의 oxalyl화 및 물이나 메탄올 부가에 의하여 octahydro-2,3-dioxo-cyclopenta[b]-pyrrole-3a-carboxylate의 6a-hydroxy- 및 6a-methoxy-유도체(1~6)를 합성하였다. 헤테로 고리의 형성은 불안정한 N-acyliminium(B)체를 경유하여 일어나며, 안정한 부가체 C (1∼6)는 endo-ene형 pyrrolinium B에 친핵체를 부가하여 얻을 수 있었다.
6a-Hydroxy- and 6a-methoxy-derivatives (1∼6) of octahydro-2,3-dioxo-cyclopenta[b]-pyrrole-3a-carboxylate were synthesized from oxalylation of enamine A, which was prepared from condensation of five-membered cyclic ${eta}$-keto ester and phenylalkylamine, followed by addition of water or methanol. The formation of heterocyclic ring was assumed to occur by the way of unstable N-acyliminium (B). Stable adduct C (1∼6) was obtained from nucleophilic addition to the endo-ene type pyrrolinium B.
