Vilsmeier - Haack reaction cyclizatlon of N-substituted -3- acetyl indole phenyl hydrazones and their reactions

ABSTRACT

New 1-phenyl -3- [N-Substitutcd indol- 3-yl] [1H] pyrazolc -4-carboxaldehydes 4a-c were synthesized in 80-85% yield via Vilsmeier - Haack reaction cyclization of N-substitutcd -3- acetyl indole phenyl hydrazones using 2.5 equivalent ratio of phosphrous oxychloride and dimethyl formamide. Reaction of compounds 4a-c with urea, thiourea and different compounds, namely ethyl acetoacetate, acetyl acetone and ethyl cyanoacctatc gave the corresponding pyrimidinc-2-one and pyrimidine-2-thionc derivatives 5a,b-13a,b. Moreover, condensation of compounds 4a-c with active methylene groups of different compounds, namely malononitrile, ethyl cyanoacetate and 2-cyanoacetohydrazide under different conditions led to the formation of pyridine derivatives 15a,b,c-21a,b