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。