“Formal” Ruthenium-Catalyzed [4+2+2] Cycloaddition of 1,6-Diynes to 1,3-Dienes: Formation of Cyclooctatrienes vs Vinylcyclohexadienes
作者:Jesús A. Varela、Luis Castedo、Carlos Saá
DOI:10.1021/ol0348710
日期:2003.8.1
[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
[反应:见正文]描述了一种新的“形式” Ru催化的1,6-二炔与[1,3-二烯]的[4 + 2 + 2]环加成反应,得到共轭的1,3,5-环辛二烯和乙烯基环己二烯。这种正式的环加成反应实际上是一个串联过程,即Ru(II)催化的(Z)-四烯或乙烯基-(Z)-三烯的形成,然后进行纯的热旋转8 pi-或旋转6 pi电环化。所提出的机制使得可以从空间和立体化学方面来解释产物比率的差异。