Potassium Carbonate → 5-Bromo-1H-thieno[3,2-c]pyrazole

Participants

Reaction Conditions

Reaction Steps

A mixture of 1-(5-bromo-thieno[3,2-c]pyrazol-1-yl)-ethanone [12.0 g, 49.0 mmol Intermediate (51)], 1,4-dioxane (120 mL), and 2 M aqueous potassium carbonate (80.0 mL) was stirred at 95° C. under nitrogen. After 20 hours, the reaction mixture was cooled to room temperature and then diluted with ethyl acetate (200 mL). The mixture was washed twice with water (100 mL) and brine (100 mL) successively, dried over magnesium sulfate, and concentrated in vacuo. The product was dried under vacuum to give 5-bromo-1H-thieno[3,2-c]pyrazole [9.48 g, 95%, Intermediate (52)] as an off-white solid. TLC Rf 0.26 (silica, 1:1 ethyl acetate/heptane); LC/MS: 202.93 (M+H), RT=2.79 minutes; 1H NMR (300 Mhz, CDCl3) δ 10.8 (br s, 1H), 7.70 (s, 1H), 7.12 (s, 1H).

Provenance & Evidence