Light-induced reactions of 2-(N-aikyi-N-arylamino)acetophenones and related amino-ketones: formation of 1,3-diarylazetidin-3-ols

Abstract

On irradiation in ether, 2-(N-methylanilino)acetophenones, Ar¹NMe·CH₂COAr²(Ar¹, Ar²= Ph, Ph; Ph,p-MeO·C₆H₄; Ph, p-Ph·C₆H₄; p-Cl·C₆H₄, Ph; p-Me0·C₆H₄, Ph; and p-Me·C₆H₄, Ph), underwent type II cyclisation to isomeric 1,3-diarylazetidin-3-ols. A minor photoproduct was one of the two expected type II fission products, the corresponding aectophenone Ar²COMe. The second type II fission product, imine Ar¹NCH2, was not detected, but in three cases a 1,3-diarylimidazolidine, probably derived from this imine, was isolated. Similar results were obtained on irradiation of the related amino-ketones, 2-(N-methylanilino)-2′-acetonaphthone and 2-(N-methylanilino)-1 -tetralone. Direct fission of the C-2-N bond occurred on irradiation of 2-(N-methylanilino)indan-1 -one and 2,2-dimethyl-2-(N-methylanilino)acetophenone. 2-(N-Alkylanilino)acetophenones, PhNR·CH₂COPh (R = Et, Me₂CH, and PhCH₂), yielded complex mixtures on irradiation.