Synthesis of New Derivatives of Heterocyclic Compounds Containing Pyridine, Pyrimidine and Triazole Ortho-Fused to Isoquinoline Moiety

Abstract

4-Amino-9,10-dimethoxy-2-phenyl-6,7-dihydro-2(H)-pyrido[2,1-a]isoquinoline-1,3-dicarbonitrile derivatives 4a-c were obtained from the reaction of 6,7-dimethoxy-3,4-dihydroisoqinoline-1-acetonitrile 1 with arylidenemalononitrile 2a-c in boiling acetonitile in the presence of piperidine. The reaction of 4a-c with triethyl orthoformate in acetic anhydride at reflux give the ethoxymethyleneamino derivatives 5a-c. Compounds 5a-c were reacted with hydrazine hydrate and give the corresponding 4-amino-3-imino-2-aryl-3,4,8,9-tetrahydro-2(H)-pyrimido[5?,4?:5,6]pyrido[2,1-a]isoquinoline-1-carbonitrile derivatives 6a-c. Refluxing compound 6a in an excess of triethyl orthoformate give 7a. When compounds 6a-c were refluxed with acetic anhydride or benzoyl chloride in pyridine, they afford the corresponding 4-methyl and 4-phenyl derivatives 8a-c and 9a-c, respectively. Compound 6a was refluxed in diethyloxalate and give product 10. Also, the reaction of 6a with C-acylhydrazonoyl halides 13a,b in refluxing chloroform in the presence of triethylamine afford 14a,b. Correct elemental analyses and spectral data (IR, 1H NMR, 13C NMR and MS) confirm the structure of the synthesized compounds.