-quinone methides 2. Stereoselectivity in cycloaddition reactions of -quinone methides with vinyl ethers
作者:Arturo Arduini、Anna Bosi、Andrea Pochini、Rocco Ungaro
DOI:10.1016/s0040-4020(01)96662-1
日期:1985.1
vinyl ethers 3 and o-quinone methides 2, thermally generated from 2-hydroxybenzyl alcohols 1, have been studied. The structure and conformational preferences of the 4-substituted 2-ethoxy-(2,3)-dihydro-2H-benzopyrans 4–9 obtained, which show new interesting features, are discussed together with competitive kinetic data. The cycloaddition process is concerted and involves o-quinone methides in the E-configuration
已经研究了由2-羟基苄醇1热生成的乙烯基醚3和邻醌甲基化物2之间的环加成反应。所获得的具有新的有趣特征的4-取代的2-乙氧基-(2,3)-二氢-2H-苯并吡喃4-9的结构和构象偏好与竞争动力学数据一起进行了讨论。环加成过程是协调的,并且涉及E构型的邻醌甲基化物。对于乙基乙烯基醚和Z-1-丙烯基乙基醚,OEt-内基过渡态似乎是优选的,而对于E-1-丙烯基乙基醚,环加成过程的立体选择性取决于起始醇1的亚甲基上的取代基。这些结果以丙烯基醚甲基的内和外优先性进行讨论。