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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 which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

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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