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Enaminones as Building Blocks in Heterocyclic Syntheses: Reinvestigating the Product Structures of Enaminones with Malononitrile. A Novel Route to 6-Substituted-3-Oxo-2,3-Dihydropyridazine-4-Carboxylic Acids
Molecules 2009, 14(1), 78-88; doi:10.3390/molecules14010078
Article

Synthesis of 5-Substituted 3-Amino-1H-Pyrazole-4-Carbonitriles as Precursors for Microwave Assisted Regiospecific Syntheses of Pyrazolo[1,5-a]Pyrimidines

1
,
2, 1,*  and 1
1 Applied Science Department, College of Technological Studies, Public Authority for Applied Education and Training, P. O. Box 42325 Safat, 70654 Kuwait 2 Chemical Engineering Technology Department, College of Technological Studies, Public Authority for Applied Education and Training, P. O. Box 42325 Safat, 70654 Kuwait
* Author to whom correspondence should be addressed.
Received: 23 November 2008 / Revised: 15 December 2008 / Accepted: 17 December 2008 / Published: 29 December 2008
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Abstract

A simple route to 3-oxoalkanonitrile 5, aprecursor of the title compounds is described. Reaction of enaminones 2 with hydroxylamine hydrochloride in ethanol yielded aldoximes 3 that were converted readily into 5 in basic medium. This method has been successfully applied with a number of substrates and resulted in excellent yields of the products. Reacting 5 with trichloroacetonitrile afforded 3-amino-2-aroyl-4,4,4-trichloro-2-butenenitriles 6 that condensed with hydrazines to yield 3-amino-1H-pyrazole-4-carbonitrilederivatives 8. Substituted pyrazolo[1,5-a]pyridmidines have been prepared with regioselective condensation reactions of 8 with nonsymmetrical dielectrophiles. The structures of compounds obtained were deduced based on 1H-NMR, 1H-15N HMBC- measurements.
Keywords: Oxoalkanonitriles; 2-Aroyl-3-dimethylamino-2-propenenitrile; Pyrazolo[1; 5-a]pyrimidines; Solvent-free reactions; 1H-15N HMBC Oxoalkanonitriles; 2-Aroyl-3-dimethylamino-2-propenenitrile; Pyrazolo[1; 5-a]pyrimidines; Solvent-free reactions; 1H-15N HMBC
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Al-Qalaf, F.; Mandani, F.; Abdelkhalik, M.M.; Bassam, A.A. Synthesis of 5-Substituted 3-Amino-1H-Pyrazole-4-Carbonitriles as Precursors for Microwave Assisted Regiospecific Syntheses of Pyrazolo[1,5-a]Pyrimidines. Molecules 2009, 14, 78-88.

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