EXPLOITATION OF INTRA-MOLECULAR PHOTO-CHEMICAL ARYLATION OF N-SUBSTITUTED ENAMINONES - EFFICIENT, GENERAL-SYNTHESIS OF HETEROCYCLIC-COMPOUNDS

A general and facile photochemical method for the introduction of aryl groups into the enaminone system and its use in preparing heterocyclic compounds of varying ring sizes have been developed. Upon the photolysis of the Nphenyl (3a, 3b, and 5), N-benzyl (3c and 7), and N-phenethyl (3d and 9) enaminones, intramolecular C-arylation proceeds to give the carbazoles (4a, 4b, and 6), the phenanthridines (9 and 10), and the benzazepines (12 and 13), respectively. On the other hand, upon the photolysis of the IV-phenethyl enaminone 15, N-arylation occurs to give the indoline 18. When the TV-phenylpropyl enaminone 3e is photolyzed, the benzazocine 22 and the tetrahydroquinoline 23 are obtained via competing process between C-C and C-N coupling, respectively. The applicability of this method to the synthesis of the naturally derived compound 28, which is related to the lycorine alkaloids, is demonstrated. © 1979, American Chemical Society. All rights reserved.