Novel reactions of 5-chloro-4-formyl-3-methyl-1-phenylpyrazole with active methylene compounds

Condensation of 5-chloro-4-formyl-3-methyl-1-phenylpyrazole (1) with malononitrile in the presence of piperidine or ammonium acetate affords the corresponding pyrazole derivatives (2-4). Base-catalyzed cyclocondensation of 1 with hippuric acid or ethyl glycinate hydrochloride gives the oxazolone 6 a...

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Published inIndian journal of chemistry. Sect. B. Organic chemistry, including medicinal chemistry Vol. 35; no. 5; pp. 426 - 430
Main Authors Shiba, SA, Harb, NMS, Hassan, MA, ElKassaby, MA, AbouElRegal, MMK
Format Journal Article
LanguageEnglish
Published NEW DELHI Council Scientific Industrial Research 01.05.1996
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
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Summary:Condensation of 5-chloro-4-formyl-3-methyl-1-phenylpyrazole (1) with malononitrile in the presence of piperidine or ammonium acetate affords the corresponding pyrazole derivatives (2-4). Base-catalyzed cyclocondensation of 1 with hippuric acid or ethyl glycinate hydrochloride gives the oxazolone 6 and 5-amino-3-methyl-6-oxo-1-phenyl-1,6-dihydropyrano[2,3-c]pyrazole (7) respectively. Treatment of 1 with ethyl cyanoacetate in basic medium produce ethyl alpha-cyano-beta-(5-chloro-3-methyl-1-phenylpyrazol-4-yl)acrylate (8) which reacts with nitrogen nucleophiles to give compounds 9-12. Transesterification and/or hydrolysis of ester group has been observed on treatment of 8 with methyl alcohol in basic medium leading to the formation of acrylate derivatives (13-15), Compound 8 on treatment with ethyl acetoacetate or cyclohexanone undergoes condensation with subsequent cyclization and/or dearylation to give the adducts 16 and 17 respectively. Structures of all the products have been established by elemental analysis, IR, PMR and mass spectral data.
ISSN:0376-4699