Reaction #531825

Reaction equation

potassium carbonate

2,3-dichloropyridine

3-bromopyrazole

product

3-bromopyrazole

→

pink solid

2-(3-bromo-1H-pyrazol-1-yl)-3-chloropyridine

Solvents

N,N-dimethylformamide

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was cooled to room temperature
2. 2
   OtherA precipitate formed
3. 3
   Filtrationfiltered
4. 4
   Washwashed with water (2×100 mL)
5. 5
   FiltrationThe solid filter cake
6. 6
   Washwashed sequentially with water, 1N hydrochloric acid, saturated aqueous sodium bicarbonate solution, and brine
7. 7
   DryingThe organic extracts were then dried over magnesium sulfate
8. 8
   Concentrationconcentrated

Procedure

To a mixture of 2,3-dichloropyridine (27.4 g, 185 mmol) and 3-bromopyrazole (i.e. the product of Step B) (25.4 g, 176 mmol) in dry N,N-dimethylformamide (88 mL) was added potassium carbonate (48.6 g, 352 mmol), and the reaction mixture was heated to 125° C. for 18 hours. The reaction mixture was cooled to room temperature and poured into ice water (800 mL). A precipitate formed. The precipitated solids were stirred for 1.5 h, filtered and washed with water (2×100 mL). The solid filter cake was taken up in methylene chloride and washed sequentially with water, 1N hydrochloric acid, saturated aqueous sodium bicarbonate solution, and brine. The organic extracts were then dried over magnesium sulfate and concentrated to afford 39.9 g of a pink solid. The crude solid was suspended in hexane and stirred vigorously for 1 hr. The solids were filtered, washed with hexane and dried to afford the title product as an off-white powder (30.4 g) determined to be >94% pure by NMR. This material was used without further purification in Step D.

Source