The Stereochemistry of the Photochemical Rearrangement of 1-Substituted 1a,7b-Dihydro-1H-cyclopropanaphthalenes under Sensitized Conditions

Article abstract of DOI:10.1246/bcsj.55.3523

The photolysis of 1-substituted 1a,7b-dihydro-1H-cyclopropanaphthalenes in the presence of Michler's ketone leads principally to 5-substituted 5H-benzocycloheptenes as primary products via a stepwise mechanism.The reaction proceeds smoothly with inversion of the migrating carbon if there is no steric hindrance, but it proceeds predominantly with retention if the inversion course is severely suppressed by steric hindrance.The marked difference in the exo-endo ratio of the secondary photocyclization products depending on the irradiation conditions was also recognized for 1-methoxycarbonylmethyl derivative.