[4 + 2]-Cycloaddition and 1,4-Addition of <i>ortho</i>-Quinone Methides by a Chiral Crotyl Silane
作者:Christopher R. Wong、Gerald Hummel、Yongqi Cai、Scott E. Schaus、James S. Panek
DOI:10.1021/acs.orglett.8b03395
日期:2019.1.4
ortho-quinone methides (oQMs). The reaction produces both the chiral chroman and crotylation products in a ratio reflective of the electronic nature of the parent oQM with overall combined yields up to 96%. A ring-opening and elimination sequence was subsequently developed to provide direct access to the crotylation products, containing two contiguous tertiary carbon stereocenters, in good yields and enantioselectivities
无水的FeCl 3在2,6-二甲基吡啶的存在促进衬底控制的对映选择性[4 + 2] -环和对映体富集(之间crotylation反应小号,ë)-crotyl硅烷和原位生成的邻-quinone甲基化物(Ô QMS )。该反应产生手性苯并二氢吡喃和crotylation产品无论在母体的电子性质的比率反射ö QM与整体合并产率高达96%。随后开发了开环和消除序列,以提供良好的收率和对映选择性,可直接获得含有两个连续的叔碳立体中心的crotylation产品。