Oxidation of aryl- and diarylcyclopropanes in a pentasil zeolite: Ring opening with deprotonation or net hydrogen migration

Incorporation of trans-1,2-diphenylcyclopropane (1) and its 3,3-D2-isotopom er into the channels of a redox-active pentasil zeolite (Na-ZSM-5) resulted in the formation of exo,exo-1,3-diphenylallyl radical (2(.)) and its 2-D1 isotopomer, respectively. This conversion requires oxidation, ring opening, and deprotonation, in an unspecified sequence. The allyl radical 2(.) is a lso formed upon incorporation of trans-1,3-diphenylpropene (3). A compariso n with the solution photochemistry, in the presence or absence of added bas e, shows the conversion of 1 into 2(.) to be a zeolite-specific reaction. I ncorporation of arylcyclopropanes 9 (R = H, OCH3) into ZSM-5 generated tran s-propenylbenzene radical cations 10(.+) (R = H, OCH3); the 2,2-D2 isotopom er of 9 (R = OCH3) gave rise to three different isotopomers of 10(.+) (R = OCH3).