反应详情

A 100ml flask was charged with 27.8 g of 5-acetylpyrazole-3-carboxylic acid ethyl ester and 40 ml of tetrahydrofuran. To this mixture, 56.4 g of phenyltrimethylammonium tribromide were added. The resulting red mixture was stirred at room temperature for 1 hour and poured into 600 ml of water. The resulting mixture was filtered and the solids were washed with more water. The solids were collected, air-dried and recrystallized from 1:1 mixture of disopropyl ether and hexanes (300ml) to afford 33.1 g of 5-(2-bromoacetyl)pyrazole-3-carboxylic acid ethyl ester as white solids, mp 174°-176° C. NMR: 1.42 (t, 3H), 4.44 (q, 2H), 4.57 (s, 2H), 7.4 (s, 1H).

1. filtrationThe resulting mixture was filtered
2. washthe solids were washed with more water
3. customThe solids were collected
4. customair-dried
5. customrecrystallized from 1:1 mixture of disopropyl ether and hexanes (300ml)