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Synthesis 2002(8): 1079-1083
DOI: 10.1055/s-2002-31955
PAPER
© Georg Thieme Verlag Stuttgart · New York

Non-Condensed Trifluoromethylated 5,5-Bicycles: Synthesis of 2-[3-Alkyl(phenyl)-1H-pyrazol-1-yl]-4-phenyl-5-alkylthiazole and -4,5,6,7-tetrahydrobenzothiazole Systems

Helio Gauze Bonacorso*, Arci Dirceu Wastowski, Mauro Neves Muniz, Nilo Zanatta, Marcos Antonio Pinto Martins
Núcleo de Química de Heterociclos - NUQUIMHE, Departamento de Química, Universidade Federal de Santa Maria, 97105-900 - Santa Maria, RS - Brazil
Fax: +55(55)2208031; e-Mail: heliogb@base.ufsm.br;
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Publication History

Received 30 November 2001
Publication Date:
03 June 2002 (online)

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Abstract

A convenient method for the synthesis of a novel series of eighteen non-condensed 5,5-bicycles, specifically 2-[3-alkyl(phenyl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazol-1-yl]-4-phenyl-5-alkylthiazoles and -4,5,6,7-tetrahydrobenzothiazoles 3a-i from the reaction of 3-alkyl(phenyl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-pyrazolethiocarboxyamide (1) with 2-bromoacetophenone, 2-bromopropiophenone and 2-bromocyclohexanone (2), is reported. The dehydration of compounds 3a-i with a mixture of concentrated sulfuric acid-acetic acid (1:10 v/v) led to the corresponding 2-[3-alky(phenyl)-5-trifluoromethyl-1H-pyrazol-1-yl]-4-phenyl-5-alkylthiazoles and respective 4,5,6,7-tetrahydrobenzothiazoles 4a-i in good yield.

Key words

thiazoles - benzothiazoles - fluorine - heterocycles - pyrazoles - cyclizations