Photochemical Cycloaddition of Phenanthrene-Fused Lactones to (E)-Anethole. Structural Effects and Dual Collapse Processes of an Exciplex Leading to Cycloadducts

Article abstract of DOI:10.1246/bcsj.66.287

On radiation with (E)-anethole in benzene 10-hydroxymethyl-9-phenanthrenecarboxylic acid lactone (s-trans lactone STL) gave an intermolecular <2 + 2> cycloadduct, a cyclobutane derivative, while 8-hydroxymethyl-9-phenanthrenecarboxylic acid lactone (s-cis lactone, SCL) afforded a cyclobutane derivative and an olefinic product derived from an oxetane precursor, the carbonyl adduct.The formation of cycloadducts of highly different structures in SCL was ascribed to competitive collapse of the involved exciplex to the products.The features of intermolecular cycloaddition of the phenanthrene derivatives are discussed on the basis of results obtained from molecular orbital calculations.