Substitution Controlled Functionalization of <i>ortho</i>-Bromobenzylic Alcohols via Palladium Catalysis: Synthesis of Chromenes and Indenols
作者:Lodi Mahendar、Gedu Satyanarayana
DOI:10.1021/jo402763m
日期:2014.3.7
transformation of simple ortho-bromobenzyl tertiary alcohols to chromenes is presented. Their formation is believed to proceed via the formation of a five-membered palladacycle, which, in turn, involves in an intermolecular homocoupling with the second ortho-bromobenzyltertiary alcohol to yield the homo-biaryl bond followed by intramolecular C–O bond formation. Interestingly, when there is an allylic substituent
提出了一种有效的多米诺骨牌钯催化的简单的邻溴苄苄基叔醇向色烯的转化。据信它们的形成是通过形成五元的palladacycle来进行的,而该五元的palladacycle又与第二邻位分子发生了分子间的均质偶联。-溴苄基叔醇产生均联-芳基键,然后形成分子内C-O键。有趣的是,当苄基碳原子上存在一个烯丙基取代基时,观察到化学选择性开关,其优选分子内Heck偶联并得到茚基。此外,已经证实叔醇官能团对于提供偶联产物必不可少,而伯/仲苄醇的使用则通过可能的还原脱溴和随后的氧化作用提供了简单的羰基产物,这归因于β-氢的存在( s)。