钌催化的1,6 - 二炔与1,3 - 二烯的“形式”[4+2+2]环加成反应：环辛三烯与乙烯基环己二烯的生成

"Formal" ruthenium-catalyzed [4+2+2] cycloaddition of 1,6-diynes to 1,3-dienes: formation of cyclooctatrienes vs vinylcyclohexadienes.

作者信息

Varela Jesús A, Castedo Luis, Saá Carlos

机构信息

Departamento de Química Orgánica y Unidad Asociada al CSIC, Facultad de Química, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.

出版信息

Org Lett. 2003 Aug 7;5(16):2841-4. doi: 10.1021/ol0348710.

DOI:10.1021/ol0348710

PMID:12889888

Abstract

[reaction: see text] A new "formal" Ru-catalyzed [4+2+2] cycloaddition of 1,6-diynes to 1,3-dienes giving conjugated 1,3,5-cyclooctatrienes and vinylcyclohexadienes is described. This formal cycloaddition is really a tandem process, the Ru(II)-catalyzed formation of (Z)-tetraenes or vinyl-(Z)-trienes followed by a pure thermal conrotatory 8 pi- or disrotatory 6 pi-electrocyclization. The proposed mechanism allows the differences in product ratio to be explained in terms of steric and stereochemical considerations.

摘要

[反应：见正文] 描述了一种新型的“形式上的”钌催化1,6 - 二炔与1,3 - 二烯的[4+2+2]环加成反应，生成共轭的1,3,5 - 环辛三烯和乙烯基环己二烯。这种形式上的环加成实际上是一个串联过程，即钌（II）催化形成（Z）-四烯或乙烯基-（Z）-三烯，随后进行纯粹的热顺旋8π或对旋6π电环化反应。所提出的机理能够根据空间和立体化学因素来解释产物比例的差异。