Phosphorus oxychloride → 4-chloro-5,7-diethyl-1,6-naphthyridin-2(1H)-one

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Reaction Steps

Compound C (17.6 g) was dissolved in phosphorus oxychloride (100 ml) and the mixture was heated at reflux for 24 hours. Unreacted phosphorus oxychloride was removed by evaporation and the residue was dissolved in concentrated hydrochloric acid (100 ml) containing water (15 ml). The mixture was heated at reflux for 4 hour. The mixture was then diluted with water (500 ml) and basified with solid potassium carbonate. The resulting precipitate was collected by filtration and washed with water. The solid was purified by flash chromatography, eluting with ethyl acetate, to give 4-chloro-5,7-diethyl-1,6-naphthyridin-2(1H)-one (D) (8.9 g); m.p. 172°-174° C.; NMR (CDCl3): 1.35(dt, 6H), 2.86(q, 2H), 3.49(q, 2H), 6.83(s, 1H), 7.0(s, 1H), 12.4(broad, 1H); mass spectrum (CI, ammonia): 237 (M+H)+ ; microanalysis, found: C, 60.3; H, 5.5; N, 11.5%; C12H13ClN2O requires: C, 60.9; H, 5.5; N, 11.8%.

Provenance & Evidence