Solvent-free one-pot cyclization and acetylation of chalcones : synthesis of some 1-acetyl pyrazoles and spectral correlations of 1-(3-(3, 4-dimethylphenyl)‎-5-(substituted phenyl)‎- 4, 5-dihydro-1H-pyrazole-1-yl)‎ ethanones

Abstract EN

One-pot synthesis of some 1N-acetyl pyrazoles including 1-(3-(3,4-dimethylphenyl)- 5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-yl) ethanones has been achieved via solvent-free microwave irradiation using substituted chalcones, hydrazine hydrate and acetic anhydride in the presence of catalytic amount of fly-ash: PTS catalyst.

The yield of these 1N-acetyl pyrazole derivatives is more than 75%.

The synthesized 1N-acetyl pyrazoline derivatives were characterized by their physical constants and spectral data.

The infrared spectral mC‚N and C‚O (cm_1) frequencies, NMR chemical shifts (d, ppm) of Ha, Hb, Hc, CH3 protons, C‚N, C‚O and CH3 carbons of 1-(3-(3,4-dimethylphenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-yl) ethanones have been assigned and correlated with Hammett substituent constants and Swain-Lupton’s parameters using single and multi-regression analysis.

From the results of statistical analyses, the effect of substituents on the above group frequencies and chemical shifts of the acetylated pyrazoles were discussed.

ھ 2013 King Saud University.

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