Photochemical reactions of 1,3-disilacyclobutanes.

Abstract

Photolysis of pure trans- or cts-l,l,3,3-tetraphenyl-2,4-dineopentyl-l,3-disilacyclobutane gives rapid isomerization to a 70/30 equilibrium mixture of the isomers and less rapid formation of ring-opened vinylsilane isomers. In the presence of MeOH, MeOSiMe3, or (EtO)3SiH as traps the expected adducts to 1,1 -diphenyl-2-neopentylsilene are also observed. Solvent dependence of the yields suggests that all of the products arise from singlet excited state(s). The results are consistent with the initial formation of a singlet ring-opened 1,4-biradical which recloses rapidly to starting material or goes on to the observed products.