Aza- and carbo-[3+3] annulations of exo-cyclic vinylogous amides and urethanes. Synthesis of tetrahydroindolizidines and an unexpected formation of hexahydroquinolines
作者:Sunil K. Ghosh、Grant S. Buchanan、Quincy A. Long、Yonggang Wei、Ziyad F. Al-Rashid、Heather M. Sklenicka、Richard P. Hsung
DOI:10.1016/j.tet.2007.09.089
日期:2008.1
Annulations of exo-cyclic vinylogous amides and urethanes with vinyl iminium salts are described here. We observed an intriguing dichotomy in their reaction pathways. For pyrrolidine- and azepane-based vinylogous amides or urethanes, aza-[3+3] annulation would dominate to give tetrahydroindolizidines, whereas, unexpectedly, for piperidine-based vinylogous amides or urethanes, carbo-[3+3] annulation was
这里描述了外环插烯酰胺和氨基甲酸酯与乙烯基亚胺盐的[3+3]环化。我们观察到它们的反应途径中存在有趣的二分法。对于基于吡咯烷和氮杂环庚烷的插烯酰胺或氨基甲酸酯,氮杂-[3+3]环化将主导产生四氢吲哚里西啶,而出乎意料的是,对于基于哌啶的插烯酰胺或氨基甲酸酯,碳-[3+3]环化是途径,产生六氢喹啉。这种对比的起源可能与初始反应途径在 C-1,2-加成和 C-1,4-加成之间的转换有关。