Functionalization and cyclization reactions of 4‐benzoyl‐1,5‐diphenyl‐ 1H‐pyrazole‐3‐carboxylic acid

Abstract

The 1H‐pyrazole‐3‐carboxylic acid 2 or its remarkably stable acid chloride 3 can easily be converted into the corresponding ester or amide derivatives 4 or 5, respectively, from reaction with alcohols or N‐nucleophiles. Pyrazolo[3,4‐d]pyridazines 6a,b are obtained from cyclocondensation reactions of the pyrazoles 2 and 3, respectively, with phenylhydrazine or hydrazine hydrate, while 6c is formed in an one‐pot procedure from the furan‐2,3‐dione 1 and hydrazine hydrate.

Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and-acid chloride with various aminophenols

“…The compound 1 can easily be transformed into the corresponding 1H-pyrazole-3-carboxylic acid chloride 2 by usual chemical procedures [12]. Substituted 2,3-furandione, acid 1 and acid chloride 2, which are used as an important initial materials in the synthesis of the target heterocycles, were prepared using the literature procedures [1,11,12,16].…”

“…A convenient method for their synthesis, the mechanism of reactions, and semi-empirical (AM1 and PM3) and ab initio (DFT) calculations on the interaction of 4-benzoyl-5-phenyl-2,3-dihydro-2,3-furandione with several semicarbazones, ureas, thioureas and anilides have been reported recently [6][7][8][9][10]. The reaction of the furan-2,3-dione with various phenylhydrazones and phenylhydrazine leads to pyrazole-3-carboxylic acid and pyridazinones [11][12][13][14].…”

Further derivatives of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and their antibacterial activities

“…The 1 H-and 13 C-NMR spectra were recorded on Varian XL-200 (200 MHz) and (50 MHz) spectrometers, respectively, using Tetramethylsilane (TMS) as an internal standard. The title compounds 1, 2, and 3 were prepared according to the literature procedure (Akçamur et al, 1986;Akçamur et al, 1997).…”

“…Both pyrazole-3-carboxylic acid 1 and its derivatives 2 and 3 were synthesized via published procedures (Akçamur et al, 1986;Akçamur et al, 1997) Direct reaction of the acid 1 with hydroxylamine hydrochloride, on an oil bath at approximately 150-155°C led to the formation of the pyrazolo [4,3-d]oxazinone 4 in about 55% yield (Scheme 2). The structure of 4 was proven based on elemental analysis and spectral data (see the Experimental section).…”

“…A literature survey revealed that, so far, the following reactions of some of these 1,4,5-trisubstitute-pyrazol-3-carboxylic acids, particularly 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid 1, obtained 4-benzoyl-5-phenyl-2,3-furandione have been partly investigated. In an attempt to help remedy this situation we decided both to extend our previous studies (Akçamur et al, 1986;Akçamur et al, 1997) on the further reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid 1 and to evaluate the antibacterial activities of the resulting compounds.…”