Photoénolisation—VIII: Stéréospécificitéet régiospécificitéde la réaction de diels-alder avec les photodiénols issus de la benzyl-2 et de l'éthyl-2 benz

Photoenols derived from 2-benzyl- and 2-ethylbenzophenone have been trapped by maleic anhydride, methyl fumarate and phenyl fumarate. Stereochemical determinations of the single adduct obtained in each case in high yield have shown unequivocally that the Diels-Alder addition proceeds from the (E,E)-dienol by an endo approach, an interaction between the dienol hydroxylic group and one of the dienophile carbonyl group being strongly determinant. These results do not eliminate the possibility that an unreactive (Z,E)-dienol be formed during the photochemical step.