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Molecules 2012, 17(10), 12225-12233; doi:10.3390/molecules171012225
Article

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

1,2,*  and 1
Received: 27 August 2012 / Revised: 23 September 2012 / Accepted: 26 September 2012 / Published: 18 October 2012
(This article belongs to the Section Organic Synthesis)
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Abstract

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 ZnCl2 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.
Keywords: benzylidenemalononitrile; 2-arylhydrazononitrile; amidoxime; cyanoindole; dimethylformamide dimethylacetal; 1,2,3-triazole benzylidenemalononitrile; 2-arylhydrazononitrile; amidoxime; cyanoindole; dimethylformamide dimethylacetal; 1,2,3-triazole
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Khalil, K.D.; Al-Matar, H.M. 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. Molecules 2012, 17, 12225-12233.

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