Diastereoselectivity in the intramolecular diels-alder reaction of dienylpropynoates
作者:David H. Birtwistle、John M. Brown、Michael W. Foxton
DOI:10.1016/s0040-4020(01)86103-2
日期:1988.1
ratio in Diels-Alder reactions of α-chiral dienes has been examined. Cycloaddition of E-3,5-hexadien-2-ol and methyl propynoate gives a mixture of all four diastereomers. Intramolecular condensation of the related ester (6) was completely regioselective however, and one stereoisomer predominated by 6.4:1. Similar results were obtained for the corresponding secondary amide, for propynoate esters of a homologous
已经检查了α-手性二烯的Diels-Alder反应中的产物比率。E-3,5-己二-2-醇和丙炔酸甲酯的环加成反应得到所有四种非对映异构体的混合物。然而,相关酯(6)的分子内缩合是完全区域选择性的,并且一种以6.4:1为主的立体异构体。对于相应的仲酰胺,同源手性二烯醇的丙酸酯和相关的3-乙酰基丙酸酯,获得了相似的结果。这些观察结果与一个简单的模型有关,在该模型中,立体选择性是由于在环加成过渡态时最小化1,3-烷基-H相互作用而引起的。