Photoinduced electron-transfer reactions of the cope and related systems

Abstract

The 9,10-dicyanoanthracene-sensitized electron-transfer photore-actions of 2,5-diaryl-l,5-hexadienes and 3,6-diaryl-2,6-octadienes were investigated in order to prove a cyclohexa-l,4-diyl cation radical intermediate in the cation radical Cope rearrangement. Stereochemical results of rearrangements and oxygenation reactions provided evidences that cation radicals of these Cope systems initially cyclize to chair cyclohexa-1,4-diyl cation radicals, through which the cation radical Cope rearrangements stereospecifically occur in a cyclization-cleavage mechanism. Similar elec-tron-transfer photoreactions of l,4-diarylbicyclo[2.2.0)hexanes further supported this mechanism. © 1990 IUPAC