Condensed Heterocycles VIA a-Heterosubstituted Phosphonate Carbanions

Abstract

In a series of papers we showed that α-heterosubstituted phosphonate carbanions in a modified Horner-Emmons reaction are useful for the preparation of a variety of classes of compounds such as enamines, desoxybenzoines, trisubstituted vinyl chlorides, enynes, and acetylenes. We found that strategically substituted diphenyl α-(aminoaryl)-α-[4-nitrophenyl] methanephosphonates react with phenylpropynal to the expected enamines. Without isolation they could be cyclized to the corresponding condensed N-heterocycles. For the reported syntheses the following arylamines were used: 4-amino-2-methylquinoline, 5-aminoquinoline, 8-aminoquinoline, 1-amino-4-nitronaphthalene, 5-amino-2,3-dihydro-1H-indene, 1, 5-diaminonaphthalene, and 1-aminoanthracene. These aminoarylsubstituted diphenyl methanephosphonates yielded the following 4-nitrophenyl substituted heterocycles: benzo[h][1,6]naphthyridine, [1,7]phenanthroline, [1,10]phenanthroline, benzo[h]quinoline, quino[8,7,h]quinoline, and naphtho[2,3,h]quinoline. The structures of these heterocycles were assigned on the basis of 1H-NMR-spectra, mass spectra, and X-ray structure analyses.