Aryl Radical Endo Cyclization of Enamidines. Selective Preparation of Trans and Cis Fused Octahydrobenzo[<i>f</i>]quinolines
作者:Lena Ripa、Anders Hallberg
DOI:10.1021/jo971158d
日期:1998.1.1
undergo intramolecular cyclization onto the enamide/enamidine double bond by 6-endo and 7-endo closure, respectively. In the 6-endo cyclization the trans/cis ratio of the formed N-protected octahydrobenzo[f]quinoline can be controlled, and selective synthesis of either the trans or the cis isomer can be achieved with triphenyltin hydride and tris(trimethylsilyl)silicon hydride, respectively. In the 7-endo
N-保护的6- [2-(2-卤代苯基)乙基] -1,2,3,4-四氢吡啶和6- [3-(2-卤代苯基)丙基] -1,2,3,4-的芳基四氢吡啶分别通过6-内和7-内封闭来分子内环化到烯酰胺/内am双键上。在6-内基环化中,可以控制形成的N-保护的八氢苯并[f]喹啉的反式/顺式比例,并且可以使用氢化三苯锡和氢化三(三甲基硅烷基)硅氢化物来实现反式或顺式异构体的选择性合成, 分别。在N-保护的八氢-1H-苯并[3,4]环庚[1,2-b]吡啶的7-内环化中,尽管选择性很低,但反式异构体占主导地位。具有低浓度的三(三甲基甲硅烷基)硅氢化物形成具有还原的酰胺//双键的氧化环化产物。