Di-.pi.-methane rearrangement. Stereochemistry
Di-.pi.-methane rearrangement. Stereochemistry
复制标题
二-π-甲烷重排。
DOI：
10.1021/ja00807a028
复制
发表时间：
1973
期刊：
影响因子：
--
通讯作者：
Jan
中科院分区：
文献类型：
--
作者：
P. Mariano;Jan
以1-苯基-3-甲基-3-（间丙烯基）环己烯（5）为模型，确定了二-x-甲烷重排反应（二-γ-甲烷到环丙烷的激发态转化）中的优先立体化学途径。直接辐照的主要产物被确定为1-苯基-5-甲基-6-乙基-（1-顺式-丙烯基）二环[3.1.基于降解和独立的合成顺序，以异构醇18和19作为关键中间体，合成了正己烷（10）及其6-内-反式-丙炔基异构体（12）。进行了光敏化和淬灭研究。本文提出了一种新的诊断方法，用于确定直接辐照反应的几种产物中的一种产物何时来自反应物的单重激发态，并将其应用于5到10和12的转化。我们的结果表明，顺式-丙烯基产品，10，是专门从5的单重激发态和反式-顺式-丙烯基异构体，12，从三重态反应的结果。本文从机理的角度将目前研究的二-x-甲烷重排反应与其它体系进行了对比，并提出了解释这些反应的立体化学和区域化学的基本原理。
The preferred stereochemical pathways in the di-x-methane rearrangement (the excited state conversion of di-7r-methanes to-cyclopropanes) have been determined, using l-phenyl-3-methyl-3-(lm-propenyl) cyclohex-1-ene (5) as the modeldi--methane system. The major products of direct irradiation were determined to be 1-phenyl-5-methyl-6-eŦífo-(1-c/s-propenyl) bicyclo [3.1. Ojhexane (10) and its 6-endo-trans-propzny\isomer (12) on the basis of degradation and independent synthetic sequences, having the isomeric alcohols, 18 and 19, as key inter-mediates. Photosensitization and quenching studies were undertaken. A novel diagnostic method for determining when one of several products of direct irradiation reactions results from the singlet excited state of reactant is presented and applied to the conversion of 5 to 10 and 12. Our results demonstrate that the c/s-propenyl product, 10, is produced exclusively from the singlet excited state of 5 and that the tra/zs-propenyl isomer, 12, results from trip-let-state reactions. The presently studied di-x-methane rearrangement is contrasted from a mechanistic view-point with other systems and rationale to explain the stereochemistry and regiochemistry of these reactions are presented.