p-Toluenesulfonic acid monohydrate → 6-Benzyl-3-(4-chlorophenyl)-2-(2,4-dichlorophenyl)-2,6-dihydropyrazolo[3,4-c]pyridin-7-one

Participants

Reaction Steps

A mixture of 5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-1H-pyrazole-3-carboxylic acid (2,2-diethoxyethyl)-amide (I-1A-1a; 528 mg, 0.92 mmol) and p-toluenesulfonic acid monohydrate (175 mg, 0.92 mmol) in toluene (5 ml) was heated to reflux in round bottom flask fitted with a Dean-Stark condenser. After 1 hour, the reaction was cooled to room temperature, and then extracted from saturated aqueous sodium bicarbonate with ethyl acetate. The combined organic layers were washed with brine, dried (MgSO4), a concentrated, in vacuo. The crude material (0.49 g) was purified on a Biotage™ Flash 40S column using 10-20-40% ethyl acetate in hexanes as eluant to afford I-1A-1b as a solid (69 mg, 16%): +ES MS (M+1) 480.1; 1H NMR (500 MHz, CD2Cl2) δ 7.50 (d, J=1.5 Hz, 1H), 7.48 (d, J=8.3 Hz, 1H), 7.42 (dd, J=8.3, 2.1 Hz, 1H), 7.38-7.27 (m, 7H), 7.18 (d, J=8.7 Hz, 2H), 6.95 (d, J=7.5 Hz, 1H), 6.42 (d, J=7.5 Hz, 1H), 5.21 (s, 2H).

Provenance & Evidence