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Molecules 2011, 16(2), 1834-1853; doi:10.3390/molecules16021834

Enaminones as Building Blocks for the Synthesis of Substituted Pyrazoles with Antitumor and Antimicrobial Activities

Department of Chemistry, Faculty of Science, University of Cairo, Giza, 12613, Egypt
Received: 12 February 2011 / Accepted: 17 February 2011 / Published: 22 February 2011
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Novel N-arylpyrazole-containing enaminones 2a,b were synthesized as key intermediates. Reactions of 2a,b with active methylene compounds in acetic acid in the presence of ammonium acetate afforded substituted pyridine derivatives 5a-d. Enaminones 2a,b also reacted with aliphatic amines such as hydrazine hydrate and hydroxylamine hydrochloride to give bipyrazoles 8a,b and pyrazolylisoxazoles 9a,b, respectively. On the other hand, treatment of 2a,b with a heterocyclic amine and its diazonium salt yielded the respective [1,2,4]triazolo[4,3-a]pyrimidines 12a,b and pyrazolylcarbonyl[1,2,4]triazolo-[3,4-c][1,2,4]triazines 14a,b. Moreover, 2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (17) was prepared via reaction of enaminone 2a with aminothiouracil (15). Cyclocondensation of 17 with the appropriate hydrazonoyl chlorides 18a-c gave the corresponding pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones 21a-c. The cytotoxic effects of compounds 2b, 14a and 17 against human breast cell line (MCF-7) and liver carcinoma cell line (HEPG2) were screened and in both lines they showed inhibition effects comparable to those of 5-fluorouracil, used as a standard. The antimicrobial activity of some products chosen as representative examples was also evaluated.
Keywords: (dimethylamino)acryloylpyrazole; hydrazonoyl chlorides; antitumor activity; antimicrobial activity (dimethylamino)acryloylpyrazole; hydrazonoyl chlorides; antitumor activity; antimicrobial activity
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Riyadh, S.M. Enaminones as Building Blocks for the Synthesis of Substituted Pyrazoles with Antitumor and Antimicrobial Activities. Molecules 2011, 16, 1834-1853.

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