The role of conformers in the reversible photocyclisation of cis-1,2-diarylethylenes. A flash-photolytic study

Abstract

Flash-photolytic experiments showed that the photocyclisation of 1,2-di(2-naphthyl)ethylene, (I^a), results in the formation of two isomeric 4a,4b-dihydro-phenanthrenes derived from two of the possible three conformers of (I^a), and differing in thermal stability by a factor of 10¹⁰.