Studies in Angular Furocoumarins: Part III. Ultraviolet Absorption Spectra of Allopsoralene Derivatives

Ultraviolet absorption spectra of allopsoralene derivatives measured in the region 200-360 mμ show that substitution of hydrogen at 4-position by phenyl group is accompanied by bathochromic shift. Reduction of furan ring causes bathochromic effect of one of the bands (B_b). The absorption spectra of angular furocoumarins viz. isopsoralenes and allopsoralenes compare fairly well with that of phenanthrene and that of psoralene is comparable with the absorption spectra of anthracene.