Complex Thermal Behavior of 11-<i>cis</i>-Retinal, the Ligand of the Visual Pigments
作者:Carlos Silva López、Rosana Álvarez、Marta Domínguez、Olalla Nieto Faza、Ángel R. de Lera
DOI:10.1021/jo801899k
日期:2009.2.6
competition between two mechanisms of very different nature. A classical internal rotation around the C11−C12 cis double bond, via a diradical transition state, accounts for the formation of the all-trans isomer. An intricate sequence of pericyclic reactions, namely a reversible [1,7]-H sigmatropic shift and a reversible 6-π-oxa-electrocyclic reaction, is responsible for the formation of 13-cis-retinal. Experiments
在加热至80℃时,11-顺-视网膜产生全反式-视网膜和13-顺-视网膜的混合物。已经通过密度泛函理论方法研究了这种异构化,并且计算结果表明性质非常不同的两种机理之间存在密切竞争。周围的C11-C12甲古典内旋顺式双键,通过二价基团的过渡状态下,占形成所有-反式异构体。周环反应的复杂序列,即可逆的[1,7] -Hσ位移和可逆的6-π-氧杂-电环反应,负责13-顺-视网膜的形成。使用11-顺式进行实验-在C19处标记有氘的视网膜证实了该机制,并且还揭示了同位素同位素产物的空前结果。