Studies on the Thermal Ring-Opening Reactions of <i>cis</i>-3,4-Bis(organosilyl)cyclobutenes
作者:Munehiro Hasegawa、Masahiro Murakami
DOI:10.1021/jo070039n
日期:2007.5.1
4-bis(organosilyl)cyclobutenes were synthesized, and their thermal ring-opening reactions were studied. The ring-opening reaction of cis-3,4-bis(trimethylsilyl)cyclobutene proceeded remarkably faster than that of cis-3,4-dimethylcyclobutene. The significant rate acceleration was explained by assuming (i) stabilization of the transition state by electron delocalization from the cyclobutene HOMO to the Si−CH3
合成了三种顺式-3,4-双(有机甲硅烷基)环丁烯,研究了它们的热开环反应。的开环反应的顺式-3,4-双(三甲基硅烷基)环丁烯显着进行比的更快顺-3,4- dimethylcyclobutene。的显著率加速度通过从环丁烯HOMO与Si-CH假设过渡状态(i)的稳定化通过电子离域解释3 σ*轨道,(ⅱ)由C-硅σ之间的分子内相互作用的基态的不稳定环和环丁烯的π轨道,以及(iii)两个大的三甲基甲硅烷基以顺式排列通过空间的空间排斥。不对称的开环反应还研究了具有电子上不同的芳基甲硅烷基的顺式-3,4-双(芳基甲硅烷基)环丁烯。向内优先级依次升高,依次为p -CH 3 OC 6 H 4 -Si,C 6 H 5 -Si,p -CF 3 C 6 H 4 -Si,这解释了甲硅烷基取代基向内优先级的起源。基于过渡状态下环丁烯HOMO和Si-Cσ*轨道之间的稳定相互作用。