V. Sareen, V. Khatri, K. Sharma
2010
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Journal
Heterocyclic Communications
Abstract
Some new 4-[(substituted-benzothiazol-2-yl)-hydrazono]-2-(substituted phenyl) -5-methyl2, 4-dihydro-pyrazol-3-one (3) have been prepared by reacting substituted benzothiazol-2-yl amine with acetoacetic ester, 2-fsubstituted benzothiazol -2-yl)-hydrazono]-3-oxo-butyric acid ethyl ester (2) react with different hydrazines to give the title compounds. These compounds are evaluated for their antimicrobial activity. The structures of all these compounds have been confirmed by I.R., 'HNMR,Mass spectra and elemental analysis data. Introduction Pyrazoles are very useful as antibacterial, antifungal and antiviral agents.In continuation of our work on heterocycliccompounds, we have synthesized some new halogenated hydrazono pyrazol-3-one. The compounds containing thiazole' nucleus along with pyrazole enhance their biological activity. Fungicidal activity was evaluated against Alternaria burnsii and Macrophomina phaseolina. The reaction of diazonium salt (formed by the diazotization of substituted benzothiazol-2-yl amino by NaNO2 in aq. HC1) with acetoacetic ester in the presence of sodium acetate and ethanol gave 2-[(substituted benzothiazol-2-yl)hydrazono]-3-oxo-butyric acid ethyl ester (2), which on further reaction with hydrazines gave title compound (3). (SCHEME-1) Result and discussion 2-[(Substituted benzothiazol-2-yl)-hydrazono]-3-oxo-butyric acid ethyl ester (2) have been prepared by diazotization of substituted benzothiazol-2-yl amino with aceto acetic ester at 0-5°C with continuous stirring for 2 5*4 h. The diazotized form has been reacted with hydrazine in presence of acetic acid on water bath for 4-5 h to yield hydrazono pyrazol-3one (3). Compound (2) showed the presence of >NH group in IR spectrum at 3375 cm" and in'H1MMR spectrum showed a singlet at δ 8.6 ppm. The IR spectrum of compound 3a showed peak at 3360 (>NH),1510(>NHN=C), 1645(>C=O),3040(aromatic)cm"IR spectrum. 'HNMR showed peaks at δ 9.2 ppm (>ΝΗ),δ 2.5ppm (-CH3) and δ 7.2-7.8 ppm for aromatic protons. Finally mass spectrum of 3a shows IvT at m/z 459 .