Novel Enhancement of Diastereoselectivity of [2 + 2] Photocycloaddition of Chiral Cyclohexenones to Ethylene by Adding Naphthalenes
作者:Ken Tsutsumi、Hiroaki Nakano、Akinori Furutani、Katsunori Endou、Abdurshit Merpuge、Takuya Shintani、Tsumoru Morimoto、Kiyomi Kakiuchi
DOI:10.1021/jo0354746
日期:2004.2.1
The additive effect on the diastereoselective [2 + 2] photocycloaddition of chiral cyclohexenones 1 to ethylene is examined. A novel and fairly efficient method of increasing the diastereoselectivity in the reaction of 1a was elucidated. The de value increased from 56% to 83% by the addition of 1-phenylnaphthalene. The major product 2a was isolated by the recrystallization of the diastereomeric mixture
考察了对手性环己烯酮1与乙烯的非对映选择性[2 + 2]光环加成反应的累加效应。阐明了一种新颖且相当有效的提高1a反应中非对映选择性的方法。通过添加1-苯基萘,de值从56%增加到83%。通过重结晶非对映异构混合物(主要/次要= 11/1)分离出主要产物2a,其X射线分析证实了2a的双环系统的绝对构型。水解除去手性助剂并随后酯化,得到光学纯的双环[4.2.0]辛酮衍生物5。从荧光光谱分析和其他实验结果来看,累加效应归因于手性环己烯酮1a和添加的萘的复杂形成。