To a stirred solution of 1(4-aminophenyl)-3-(3-pyridyl)-5-ethylpyrazole (300 mg, 1.14 mmol) and 2-chloro-6-fluorobenzaldehyde (360 mg, 2.27 mmol) in 5% HOAc/MeOH (6 mL) at room temperature under argon was added sodium cyanoborohydride (180 mg, 2.86 mmol). The reaction mixture was stirred at room temperature for 4 h and then concentrated, diluted with water, extracted into ethyl acetate and washed with brine. The residue obtained on concentration was chromatographed on silica gel (eluant, gradient of 25-50% EtOAc in hexane) to provide the title compound as an oil which solidified on trituration with ether/petroleum (152 mg, 32%). m.p. 123-5° C. NMR (CDCl3, 400 MHz): 9.1 (s, 1H); 8.6 (br, 1H); 8.2 (br, 1H); 7.4-7.2 (overlapping m, 5H), 7.05 (m, 1H), 6.8 (d, 2H), 6.6 (s, 1H), 4.6 (s, 2H), 4.4 (br, 1H), 2.7 (q, 2H), 1.2 (t, 3H).
