Synthesis of Functionalized 1,4-Cyclohexadienes through Intramolecular Anionic Dearomatization of <i>N</i>-Alkyl-<i>N</i>-benzyldiphenylphosphinamides. Insight into the Reaction Mechanism
作者:Ignacio Fernández、Angela Forcén-Acebal、Santiago García-Granda、Fernando López-Ortiz
DOI:10.1021/jo0342370
日期:2003.5.1
intramolecular nucleophilic dearomatization-electrophilic alkylation reactions of N-alkyl-N-benzyldiphenylphosphinamide anions is presented. The process has been optimized by analyzing the effects of metalation and quench times, additives, the nature of the electrophiles used (MeI, CF(3)SO(3)Me, Me(3)O(+)BF(4)(-), AllylBr, PhCH(2)Br, BrCH(2)CO(2)Me, and RCH=O, where R = Ph, 4-Cl-C(6)H(4), 4-MeO-C(6)H(4), and
介绍了N-烷基-N-苄基二苯基次膦酰胺阴离子的分子内亲核脱芳香化-亲电烷基化反应的一般化。通过分析金属化和淬火时间,添加剂,所用亲电试剂的性质(MeI,CF(3)SO(3)Me,Me(3)O(+)BF(4)(- ),烯丙基溴,PhCH(2)Br,BrCH(2)CO(2)Me和RCH = O,其中R = Ph,4-Cl-C(6)H(4),4-MeO-C(6 )H(4)和(i)()Pr),以及与次膦酰胺氮原子相连的烷基取代基。HMPA和DMPU均充当催化剂。事实证明,后者对于获得高产率的含有1,4-环己二烯系统的具有很高区域和非对映选择性的取代四氢苯并[c] [1,2] -1lambda(5)-磷脂具有更高的效率。苄基阴离子附近的立体效应倾向于降低阴离子环化的立体选择性。优化研究还通过鉴定几种中间物种并显示了阴离子环化步骤以及与醛的反应的可逆性,阐明了脱芳香化过程的反应机理。