Photocyclisation of enamides. Part 15. Syntheses of the basic structures of corynoline and related alkaloids

Abstract

10b-Substituted 4b,5,6,10b,11,12-hexahydro-5-methylbenzo[c]phenanthridines (III) and (IV) were prepared by photocyclisation of the enamide (II). Isomerisation of the trans-benzo[c]phenanthridones (III) into the cis-isomers (IVa and b) and stereoselective introduction of a hydroxy group into the 11- and 12-positions by peracid provided a route towards the corynoline group of alkaloids.