PHOTOCHEMICAL TRANSFORMATIONS. 35. STEREOCHEMISTRY OF ELECTRON TRANSFER FROM PHOTOEXCITED AROMATIC RINGS TO CARBON-CHLORINE BONDS. SYN STEREOCHEMISTRY OF MIGRATION IN PHOTO-WAGNER-MEERWEIN REARRANGEMENTS.

Article abstract of DOI:10.1021/ja00363a022

Studies have been conducted on the ground-state and excited-state solvolyses of the 7,8-dichloro derivatives of benzonaphthobicyclo left bracket 2. 2. 2 right bracket octadiene and benzoveratrobicyclo left bracket 2. 2. 2 right bracket octadiene. The silver ion assisted ground-state reactions proceed, as anticipated, with clean anti stereochemistry (inversion at the migration terminus) reflected in the Wagner-Meerwein rearranged solvolysis products. Unlike the previously reported observations that excitation transfer from an photoexcited benzene ring to a beta -carbon-chlorine bond requires anti stereochemistry, electron transfer from excited naphthalene or veratrole rings occurs to both syn and anti carbon-chlorine bonds, although that to the latter is preferred. The results are consistent with an electron-transfer process to give a zwitterionic biradical and are rationalized by the Weller equation.