Condensation of 2-(4-chlorophenyl)-1-(2,4-dihydroxyphenyl) ethanone with N,N-dimethylformamide dimethyl acetal: an effective approach to 3-(4-chlorophenyl)-7-methoxy-4H-chromen-4-one, N,O- and N,N-heterocycles

[graphic not available: see fulltext] A convenient sequence for the preparation of 2-(4-chlorophenyl)-1-(2,4-dimetoxyphenyl)-3-(dimethylamino)prop-2-en-1-one has been developed. It has been demonstrated that the use of 1-(2,4-dihydroxyphenyl)ethanone or 1-(2-hydroxy-4-methoxyphenyl)ethanone in a condensation reaction with N,N-dimethylformamide dimethyl acetal leads to their heterocyclization to give an isoflavone. Reactions of the enamino ketone with N,O- and N,N-binucleophiles have been studied; as the result, 4,5-diarylisoxazole, 4,5-diarylpyrazoles, and 4,5-diaryl-substituted 2-aminopyrimidine have been obtained in good yields.