Photoreactivity of quinoline derivatives. Part 2. Photodimers of trans-4-styrylbenzo[h]quinoline

Abstract

The solution-phase photochemistry of trans-4-styrylbenzo[h]quinoline (1) was reinvestigated with the aim of obtaining more detailed information about the photodimerization reaction. Four new isomeric (benzoquinolyl)-diphenylcyclobutanes (5)–(8) were isolated in addition to the previously described cyclobutane derivative (4). Mass and ¹H n.m.r. spectra provided valuable information about the structures, configurations, and conformations of these compounds. The effects of monomer concentration, irradiation time, and the presence of oxygen are briefly discussed with a view to preparative applications of the photodimerization.