Studies on 2-arylhydrazononitriles: synthesis of 3-aryl-2-arylhydrazopropanenitriles and their utility as precursors to 2-substituted indoles, 2-substituted-1,2,3-triazoles, and 1-substituted pyrazolo[4,3-d]pyrimidines.
Coupling of 2-benzylmalononitrile with aromatic diazonium salts afforded 3-phenyl-2-arylhydrazonopropanenitriles 4a,b, which were rearranged into 2-cyanoindoles 5a,b upon heating with ZnCl(2) in the presence of glacial acetic acid. The produced indole derivatives 5a,b can be successfully used as valuable precursors to synthesize 1,2,4-oxadiazolylindoles 8a,b. The reaction of arylhydrazononitriles 4a,b with hydroxylamine afforded an amidoximes 9a,b that could be cyclized into 1,2,3-triazole-4-amines 10a,b. In addition, 4a,b could be converted into 4-aminopyrazoles 12a,b via condensation with chloroacetonitrile in the presence of triethylamine as a basic catalyst. Finally, compounds 12a,b were refluxed with dimethylformamide dimethylacetal (DMFDMA) to afford amidines 13a,b that were readily cyclized to the corresponding pyrazolo[4,3-d]pyrimidines 14a,b when refluxed with ammonium acetate.
Chemistry Department, Faculty of Science, University of Kuwait, P.O. Box 5969, Safat 13060, Kuwait. khd.khalil@yahoo.com
Khaled D
KD
Khalil
Hamad M
HM
Al-Matar
D007211:Indoles / Q000737:chemistry; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry; D014230:Triazoles / Q000737:chemistry
D007211:Indoles; D009570:Nitriles; D011720:Pyrazoles; D011743:Pyrimidines; D014230:Triazoles