Influence of wavelength on the photochemistry of triarylbenzofurodioxin derivatives

Abstract

The u.v. irradiation of a number of triarylfurobenzodioxins has been carried out at both λ >280 nm and at 254 nm. The outcome of the reaction is to some extent dependent both on the substitution pattern on the bridgehead (9a) aryl group and on the wavelength. For example irradiation through Pyrex of the parent in the series 5,6,7,8-tetrachloro-3a,9a-dihydro-2,3,9a-triphenylfuro[2,3-b](1,4)benzodioxin yields only 2-phenylphenanthro[9,10-b]furan while irradiation at 254 nm yields 2-phenylphenanthro[9,10-b]furan and 2,3,5-triphenylfuran.