Three cis-3, 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 σ* orbital,(ii) ...
