Photocyclisation of enamides. Part 13. Substituent effects in the photocyclisation of N-benzoylenamines

Abstract

trans- Hexahydrophenanthridones(IIa–g) and trans-tetrahydrobenzo[c]phenanthridones(VIa–e)were prepared by stereospecific photocyclisation of a variety of N- benzoyenamines (Ia–n) and (Va–g) bearing either electron-donating or -attracting substituents on the benzoyl group. Suprafacial [1,5] migration of an o-methoxy-group upon cyclisation and photoinduced trans–cis-isomerisation of some benzo[c] phenenthrdones (VIa–c) were observed.