Characterization of tetraene intermediates formed in the [3+2]-photocycloaddition of 1,4-dicyano-6-methylnaphthalene with styrene

摘要

The early stages of the [3+2]-photocycloaddition of 1,4-dicyano-6- methylnaphthalene (6) with styrene (7) were investigated by UV-visible absorption and 1H NMR spectroscopy. An intermediate species was detected and characterized as 8-methyl-2-phenyl-1,2,2a,8- tetrahydroacenaphthylene-2a,5-dicarbonitrile (9). Computational studies explained the regioselective [3+2]-photocycloaddition at the 4,5-position of 6 to form zwitterion 8, and subsequent thermal transformation to form 9.