Reduced 3,4′-bipyrazoles carrying thiophene and thiazole substituents : structures of two intermediates and two products
Abstract
Cycloaddition reactions between 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(thiophen-2-yl)prop-2-en-1-ones and thiosemicarbazide leads to the formation of reduced 3,4′-bipyrazole-2-carbothioamides. Further cycloaddition of these intermediates with either diethyl acetylenedicarboxylate or 4-bromophenacyl bromide leads to reduced 3,4′-bipyrazoles carrying oxothiazole or thiazole substituents, respectively. The structures of two representative intermediates and two representative products established unambiguously the regiochemistry of the cycloaddition reactions. The molecules of 3′-methyl-5′-(2-methylphenoxy)-1′-phenyl-5-(thiophen-2-yl)-3,4-dihydro-1′H,2H-3,4′-bipyrazole-2-carbothioamide, C25H23N5OS2 (Ia), are linked by N—H⋯N hydrogen bonds to form simple C(8) chains. The analogous compound 5′-(2,4-dichlorophenoxy)-3′-methyl-1′-phenyl-5-(thiophen-2-yl)-3,4-dihydro-1′H,2H-3,4′-bipyrazole-2-carbothioamide hemihydrate crystallizes as a hemihydrate, C24H19Cl2N5OS2·0.5H2O (Ib), and the independent components are linked into a chain of spiro-fused R44(20) rings by a combination of O—H⋯N and N—H⋯O hydrogen bonds. In the structure of ethyl (Z)-2-{2-[3′-methyl-1′-phenyl-5-(thiophen-2-yl)-5′-(2-methylphenoxy)-3,4-dihydro-1′H,2H-3,4′-bipyrazole-2-yl]-4-oxo-4,5-dihydrothiazol-5-ylidene}acetate, C31H27N5O4S2 (II), inversion-related pairs of molecules are linked by paired C—H⋯π(arene) hydrogen bonds to form cyclic centrosymmetric dimers, but there are no direction-specific intermolecular interactions in 4-(4-bromophenyl)-2-[5′-(2,4-dichlorophenoxy)-3′-methyl-1′-phenyl-5-(thiophen-2-yl)-3,4-dihydro-1′H,2H-3,4′-bipyrazole-2-yl]-4-thiazole, C32H22BrCl2N5OS2 (III). Comparisons are made with the structures of some related compounds.
Citation
Chinthal , C H , Yathirajan , H S , Manju , N , Kalluraya , B , Foro , S & Glidewell , C 2021 , ' Reduced 3,4′-bipyrazoles carrying thiophene and thiazole substituents : structures of two intermediates and two products ' , Acta Crystallographica Section E: Crystallographic Communications , vol. 77 , no. Part 4 , pp. 335-340 . https://doi.org/10.1107/S2056989021002310
Publication
Acta Crystallographica Section E: Crystallographic Communications
Status
Peer reviewed
ISSN
2056-9890Type
Journal article
Rights
Copyright © 2020 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Description
HSY thanks the University Grants Commission, New Delhi for the award of a BSR Faculty Fellowship for three years.Collections
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