Mild and Ecofriendly Tandem Synthesis, and Spectral and Antimicrobial Studies of N¹-Acetyl-5-aryl-3-(substituted styryl)pyrazolines

Abstract

N 1 -acetyl-5-aryl-3-(substituted styryl)pyrazolines were synthesized by the cyclocondensation of 1,5-substituted diphenyl-1,4-pentadien-3-ones with hydrazine hydrate and a cyclizing agent such as acetic acid in ethanol. The title compounds were synthesized using conventional and solvent-free approaches, which involves mechanochemical mixing, microwave-irradiation, and ultrasound-irradiation methods in the presence of a solid support. The synthesized compounds have been characterized by elemental analyses and spectral data (IR, PMR, and FAB-mass). All the synthesized compounds have been evaluated for their antibacterial and antifungal activities. Some compounds have shown promising biological activity.

Styrylpyrazoles: Properties, Synthesis and Transformations

“…The cyclocondensation of (1E,4E)-1,5-diarylpenta-1,4-dien-3-one 29 with hydrazine or phenyl hydrazine in glacial acetic acid at reflux [57,58], in the presence of sulfuric acid [59], or cellulose sulfonic acid [60]…”

“…The cyclocondensation of (1 E ,4 E )-1,5-diarylpenta-1,4-dien-3-one 29 with hydrazine or phenyl hydrazine in glacial acetic acid at reflux [ 57 , 58 ], in the presence of sulfuric acid [ 59 ], or cellulose sulfonic acid [ 60 ], afforded 5-aryl-3-styryl-4,5-dihydro-1 H -pyrazoles (pyrazolines) 15 or 30 ( Scheme 4 ). Following a similar approach, Nauduri et al synthesized a series of 5-aryl-1-phenyl-3-styryl-4,5-dihydro-1 H -pyrazoles by condensation of 29 analogues with phenyl hydrazine hydrochloride in a mixture of ethanol and chloroform, in the presence of a catalytic amount of concentrated HCl (70–77%) [ 34 ].…”

“…In turn, pyrazolines 15 were converted into the corresponding pyrazoles by oxidation (dehydrogenation) ( Scheme 4 ). Several oxidant agents can be employed for this transformation; some common examples include lead tetraacetate [ 58 ], DMSO in open air [ 61 ], MnO 2 [ 62 ], p -chloranil [ 63 ], 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) [ 64 ], Pd/C [ 65 ]. In 2014, Ananthnag et al developed a simple and high yielding method for the conversion of ( E )-3- and 5-styrylpyrazolines into the corresponding pyrazoles via iron(III) catalyzed aerobic oxidative aromatization [ 65 ].…”

Synthesis and antifungal activity of novel pyrazolines and isoxazolines derived from cuminaldehyde

“…12) As for pyrazoline, many kinds of pyrazoline derivatives, especially N-acetylated pyrazoline derivatives, have been reported to show significant antifungal activities. 9,[13][14][15][16] Concerning the synthesis of isoxazolines and pyrazolines, the methods with stable and easily accessed starting materials and those conducted under mild conditions are more acceptable. 15) Usually, the sophisticated way to synthesize isoxazoline and pyrazoline is by the cyclization of α,β-unsaturated carbonyl compounds (chalcones) with hydroxylamine and hydrazine.…”

Recent Advances in the Ultrasound-Assisted Synthesis of Azoles

“…The same reaction carried out by simply heating the reaction mixture (80 °C) produced the products in lower yields (60-75%) and required longer reaction times (6-9 h). In 2009, Pathak and co-workers (Pathak et al, 2009) conducted a comparative study between four activating methods for obtaining N-acetyl-pyrazolines (7), including reflux, solvent-free conditions, microwave irradiation and ultrasonic irradiation. Microwave irradiation was found to be the most efficient activating method, followed by ultrasound.…”