C_1-C_2 Bond Cleavage in Vinylidenecyclopropanes:Theoretical Density Functional Theory Study

摘要

Density functional calculations at the B3LYP/6-31G level were carried out to investigate the photo rearrangements in 1,1-diarylvinylidene-2,3-dimethyl-and 1,1-diarylvinylidene-2,2,3,3-tetramethylcyclopropanes.Among the five different routes considered,none except the one leading to the final products of butatriene derivatives (route 4)was found to be able to explain the experimental findings only.However,the route 4 points out on the involvement of the C_1-C_2 bond cleavage in straied cyclopropane ring.Thus,a new mechanism that results in successive transformations was suggested to explain this distinct C_1-C_2 bond cleavage in cyclopropane ring for both precursors leading to formation of butatriene derivatives.The results of calculations indicate that photochemistry of vinylidenecypropane derivatives is significantly different than int he case of methylenecyclopropane compounds.