Benzoylhydrazine → Toluene-4-sulfonic acid 3-cyclopentyl-4-methyl-7-phenylpyrazolo[1,5-d][1,2,4]triazin-2-yl ester

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Reaction Conditions

Reaction Steps

Toluene-4-sulfonic acid 5-acetyl-4-cyclopentyl-1H-pyrazol-3-yl ester (0.65 g, 1.87 mmol) and benzhydrazide (0.28 g, 1.1 molar eq) were stirred together in xylene (20 ml) at reflux for 2.5 h. The solvent was reduced to ˜5 ml and Dowtherm A (20 ml) was added and the reaction mixture was heated at 180° C. for 2 h. The mixture was cooled and poured directly onto a column of silica gel, and the Dowtherm was eluted off with dichloromethane before eluting the product off with 3-6% ethyl acetate in dichloromethane (UV detection). Toluene-4-sulfonic acid 3-cyclopentyl-4-methyl-7-phenylpyrazolo[1,5-d][1,2,4]triazin-2-yl ester was obtained as a light brown solid (0.62 g). 1H NMR (360 MHz, CDCl3) δ 1.73-2.07 (8H, m), 2.49 (3H, s), 2.91 (3H, s), 3.48 (1H, m), 7.26-7.61 (5H, m), 7.93-7.97 (2H, m), 8.13-8.15 (2H, d, J=8.7 Hz); MS (ES+) m/e 449 [MH]+.

Provenance & Evidence