反应详情

A 2 L flask was charged with 44.6 g of 1-(2,6-dichlorophenyl)-5-methyl-1H-pyrazole-3-carboxylic acid ethyl ester (133 mmol), 28.43 g of N-bromosuccinimide, 0.80 g of benzoyl peroxide and 1 L of carbon tetrachloride. The resulting solution was placed under a high intensity lamp for 2 hours. The resulting solution was allowed to cool to room temperature, filtered through a pad of celite. The filtrate was then concentrated in vacuo and the crude bromide was passed through a plug of silica using 40% EtOAc:hexane and recrystallized from heptane-ethanol to afford 5-bromomethyl-1-(2,6-dichlorophenyl)-1H-pyrazole-3-carboxylic acid ethyl ester was recovered as a tan solid (19.3 g, 38%); 1H NMR (400 MHz, CDCl3): δ 7.45 (m, 4H), 7.05 (s, 1H), 6.77 (s 0.2H starting material), 4.43 (q, J=7.07 Hz 2H), 4.27 (s, 2.16H), 2.14 (s, 0.6H starting material); 1.41 (t, J=7.07 Hz 3H), MS (ES): 399 [M+Na]+.

1. filtrationfiltered through a pad of celite
2. concentrationThe filtrate was then concentrated in vacuo
3. customhexane and recrystallized from heptane-ethanol