Lithiated Benzothiophenes and Benzofurans Require 2-Silyl Protection to Avoid Anion Migration
作者:Marvin M. Hansen、Marcella T. Clayton、Alexander G. Godfrey、John L. Grutsch Jr.、Sandra S. Keast、Dan T. Kohlman、Andreea R. McSpadden、Steven W. Pedersen、Jeffrey A. Ward、Yao-Chang Xu
DOI:10.1055/s-2004-825609
日期:——
2-Trimethylsilyl protection of benzothiophenes and benzofurans prevents anion migration to the 2-position when lithiated species are formed. These lithiated benzothiophenes and benzofurans provide superior results in additions to piperidones. Deprotection is conveniently achieved under acidic conditions. Direct C-7 metalation of benzothiophene is enabled by 2-triisopropylsilyl protection at C-2.
对苯并噻吩和苯并呋喃进行 2-三甲基硅保护,可防止形成石碳酸化物时阴离子迁移到 2-位。这些石碳酸化的苯并噻吩和苯并呋喃在与哌啶酮的加成反应中具有优异的效果。在酸性条件下可以方便地进行脱保护。通过在 C-2 位置进行 2-三异丙基硅烷保护,可实现苯并噻吩的直接 C-7 金属化。