Two isostructural 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(thiophen-2-yl)prop-2-en-1-ones: disorder and supramolecular assembly

Abstract

Two new chalcones containing both pyrazole and thiophene substituents have been prepared and structurally characterized. 3-(3-Methyl-5-phenoxy-1-phenyl-1H-pyrazol-4-yl)-1-(thiophen-2-yl)prop-2-en-1-one, C23H18N2O2S (I), and 3-[3-methyl-5-(2-methylphenoxy)-1-phenyl-1H-pyrazol-4-yl]-1-(thiophen-2-yl)prop-2-en-1-one, C24H20N2O2S (II), are isomorphous as well as isostructural, and in each the thiophene substituent is disordered over two sets of atomic sites having occupancies 0.844 (3) and 0.156 (3) in (I), and 0.883 (2) and 0.117 (2) in (II). In each structure, the molecules are linked into sheets by a combination of C—H...N and C—H...O hydrogen bonds. Comparisons are made with some related compounds.

Reduced 3,4′-bipyrazoles carrying thiophene and thiazole substituents: structures of two intermediates and two products

“…Structures have been reported recently for a number of compounds related to those reported here, including precursors and intermediates in the synthetic pathways to compounds (I)-(III). The structures of five examples of 5-aryloxy-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehydes have been reported (Shahani et al, 2011;Vinutha et al, 2014;Glidewell et al, 2019;Kiran Kumar et al, 2019), as have those (Shaibah et al, 2020) of two isostructural chalcones derived from two such carbaldehydes by condensation reactions with 2-acetylthiophene, in each of which the thiophene unit shows the same type of disorder as observed here in compounds (Ia), (Ib), (II) and (III). Structures have also been reported (Cuartas et al, 2017;Kiran Kumar et al, 2019) for several reduced 3,4 0 -bipyrazoles formed by cyclocondensation reactions between chalcones and hydrazine followed by Nacetylation.…”

“…In this connection, a procedure has recently been developed (Manju et al, 2019) for the synthesis of reduced 3,4 0 -bipyrazoles incorporating other heterocyclic units such as thiazole, thiazoline and thiophene as integral components. In brief, condensation of a 5-aryloxy-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde with 2-acetylthiophene gives the corresponding chalcone (Shaibah et al, 2020); chalcones of this type can undergo cyclocondensation reactions with semicabazide to provide the intermediate carbothioamides of type (I) (see Scheme). Further condensation of type (I) intermediates with diethyl acetylenedicarboxylate or with 4-bromophenacyl bromide gave the oxothiazolylidene ester (II) or the thiazole (III), respectively (see Scheme).…”

Formation of 1-(thiazol-2-yl)-4,5-dihydropyrazoles from simple precursors: synthesis, spectroscopic characterization and the structures of an intermediate and two products

“…The reaction sequence is summarized in Fig. 1: a base-catalysed condensation reaction between ISSN 2056-9890 4-methoxybenzaldehyde (A) and a substituted acetophenone (B) yields the chalcone intermediate (I) (Shaibah et al, 2020). Compound (I) undergoes a cyclocondensation reaction with a thiosemicarbazide to provide thioamide intermediate (C), which in turn undergoes a further cyclocondensation reaction with a phenacyl bromide to give the thiazolyl-dihydropyrazoles (II) and (III) .…”

“…For the synthesis of compound (I), 4-methoxybenzaldehyde (A), (see Fig. 1) (1.80 g, 0.014 mol) was added to a well-stirred solution of 4-(prop-2-ynyloxy)acetophenone (B) (2.00 g, 0.012 mol) and potassium hydroxide (0.90 g, 0.017 mol) in ethanol (10 ml), and this resulting mixture was stirred at ambient temperature for 5 h. When the reaction was complete, as judged from TLC, the mixture was poured into an excess of ice-cold water and the resulting solid product (I) was collected by filtration and crystallized from a mixture of ethanol and N,N-dimethylformamide (3:2, v/v) (Shaibah et al, 2020). Yield 88%, m.p.…”