Intramolecular Photocycloaddition of the C=C Double Bond to the CN Triple Bond Resulting in the Formation of a Novel Cyclic System

Article abstract of DOI:10.1246/bcsj.67.1769

Irradiation of a bichromophoric 1-(o-cyanobenzyloxy)-2-(p-methoxyphenyl)-2-butene (1a) in cyclohexane gave an isoquinoline derivative, 8-methoxy-6-methyl-11,13-dihydro<2>benzoxepino<5,4-c>isoquinoline (2a). The structure was determined by X-ray analysis. The formation of 2a can be accounted for by the initial cycloaddition of 1a in the excited singlet state between the C=C double bond and C<*>N triple bond, followed by cleavage of the resulting azetine ring and recyclization.