Title: The regioselectivity of the formation of 2-pyrazolylthiazoles and their precursors from the reaction of 2-hydrazinothiazoles with 4,4,4-trifluoro-1-hetaryl-1,3-butanediones
Authors: Denisova, AB ×
Sosnovskikh, VY
Dehaen, Wim
Toppet, Suzanne
Van Meervelt, Luc
Bakulev, VA #
Issue Date: Jan-2002
Publisher: Elsevier science sa
Series Title: Journal of Fluorine Chemistry vol:115 issue:2 pages:183-192
Abstract: Reaction of 2-hydrazinothiazoles 1 with 1-thienyl- and 1-furyl-1,3-butanediones 2a,b in methanol in the presence of hydrochloric acid mainly leads to a mixture of pyrazoles 3 and pyrazolines 4 or pyrazoles 3 and 5 in strong acidic conditions. Isomeric hydrazones 6 and pyrazolines 4 were formed and isolated in these reactions in the absence of hydrochloric acid. It has been shown that the regioselectivity in the reaction of diketones 2 with hydrazine 1 is governed by both the concentration of acid and the nature of substituents in the 1,3-diketones 2. Cyclization of hydrazones 6 is shown to occur under milder conditions than dehydration for pyrazolines 4. The new heterocyclic compounds were prepared and fully characterized by NMR spectra and by X-ray analysis for 3c. (C) 2002 Elsevier Science B.V. All rights reserved.
ISSN: 0022-1139
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Design and Synthesis
Biochemistry, Molecular and Structural Biology Section
× corresponding author
# (joint) last author

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