Oxidative Cyclization of Chalcones in the Presence of Sulfamic Acid as Catalyst. Synthesis, Biological Activity, and The
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xidative Cyclization of Chalcones in the Presence of Sulfamic Acid as Catalyst. Synthesis, Biological Activity, and Thermal Properties of 1,3,5-Trisubstituted Pyrazoles J. D. Bhiruda, G. R. Guptab,*, and H. P. Narkhedec,** a
School of Chemical Sciences, Moolji Jaitha College, Jalgaon, 425002 India b
c
Gajamal Tulshiram Patil College, Nandurbar, 425412 India
Smt. Padambai Kapurchandji Kotecha Mahila Mahavidyalaya, Bhusawal, 425201 India e-mail: *[email protected]; **[email protected] Received May 29, 2020; revised June 16, 2020; accepted June 30, 2020
Abstract—1-Aroyl-3,5-diaryl-1H-pyrazoles were synthesized by oxidative cyclization of chalcones with benzohydrazide and 4-nitrobenzohydrazide using sulfamic acid as a catalyst. The corresponding chalcones were prepared by condensation of aromatic aldehydes with acetophenones in PEG-400 in the presence of potassium hydroxide. Some representative features of the proposed procedure include exceptional regioselectivity, comparatively short reaction time, operational simplicity, and no need of external oxidant. The synthesized pyrazole derivatives were screened as antibacterial agents against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhi by the agar well diffusion method. Attempts were made to compute specific heat capacity of the synthesized pyrazole derivatives as a function of temperature using TGA– DSC in order to avail thermodynamic database for these biologically relevant heterocycles. Keywords: sulfamic acid, pyrazoles, antibacterial activity, thermal analysis, specific heat capacity
DOI: 10.1134/S1070428020100243 INTRODUCTION Nowadays, even a superficial glimpse into the modern chemistry as well as biochemistry books unveils the significance of heterocyclic compounds and highlights their role in the life-governing processes [1–7]. Pyrazoles and their analogs are structural motifs with limited access in nature. However, these structural motifs have been extensively explored as pesticides in agriculture, and they have found applications as antibacterial, antidepressant, anticonvulsant, ulcerogenic, herbicidal, anticancer, insecticidal, antihyperglycemic, analgesic, anti-inflammatory, sedative, antipyretic, and antispasmodic agents [8–16]. Furthermore, these heterocycles are considered as versatile ligands in coordination chemistry and are utilized as optical brighteners, detergent additives, UV-stabilizers for polystyrene, and highly selective fluorescence sensors [17–24]. It is therefore of great interest for synthetic organic chemists to explore several prospects for the development of highly efficient synthetic strategies to access these privileged frameworks. In this context, the reaction of structurally diverse hydra-
zines with wide variety of α,β-unsaturated ketones gives rise to highly substituted pyrazole derivatives in the presence of various catalyst such as I2 [25], (diacetoxy-λ3-iodo)benzene [26], HBr/AcOH [27], zeolite [28], Zn(OTF)2 [29], copper trifluoromethanesulfonate [14], SiO2/H2SO4 [30],
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