Enantio- and regioselective syntheses of the pyrrolidine 5,5-trans-lactams benzyl (3aS,6aR)-6,6-dimethyl-5-oxohexahydropyrrolo[3,2-b]pyrrole-1(2H)-carboxylate and benzyl (3aS,6aR)-6S-ethyl-5-oxohexahydropyrrolo[3,2-b]pyrrole-1(2H)-carboxylate from a common intermediate 2-ethoxy-3S-(2,2,2-trifluoro-acetylamino)-pyrrolidine-1-carboxylic acid benzyl ester are reported. The key step in both syntheses is the acyl iminium ion mediated condensation of the pyrrolidine with a ketene acetal.
报道了从共同中间体2-乙氧基-3S-(2,2,2-三
氟乙酰氨基)-
哌啶-1-羧酸苄酯合成的对映体选择性和区域选择性合成
吡咯烷5,5-trans-内酯,分别是苄基(3aS,6aR)-6,6-二甲基-5-氧基六氢
吡咯[3,2-b]
吡咯-1(2H)-
羧酸酯和苄基(3aS,6aR)-6S-乙基-5-氧基六氢
吡咯[3,2-b]
吡咯-1(2H)-
羧酸酯。这两种合成的关键步骤是
哌啶与酮烯醇缩合的酰基亚
氨离子介导的反应。