THE STRUCTURE OF THE DIHYDROHEXAHELICENE FORMED BY THE IRRADIATION OF STYRYL BENZOPHENANTHRENE UNDER ANAEROBIC CONDITIONS

Article abstract of DOI:10.1016/0040-4020(82)80056-2

According to Wismontski and Fischer irradiation under anaerobic conditions of 2-styryl benzophenanthrene (1) gives rise to an isolable dihydrohexahelicene which is easily oxidized into hexahelicene.Its structure obviously different from 5,6-dihydrohexahelicene 4 was elucidated by the analysis of the 500 MHz-NMR spectrum.The structure and configuration: trans-6a, 16d- dihydrohexahelicene with the 16d hydrogen oriented inside the inner helix must be formed by a suprafacial 1,5-H shift of only one hydrogen from the primary formed photocyclization product 2.