1H-Pyrazole, 1-(2-bromoethyl)-5-(bromomethyl)-3-nitro- synthesis

Yield:1227210-31-2 81%

Reaction Conditions:

with phosphorus tribromide in chloroform; for 2 h;Reflux;

Steps:

Synthesis of 1 -(2-bromoethyl)-5-(bromomethyl)-3-nitro- 1H-pyrazole (23)

To a stirred suspension of (1-(2-bromoethyl)-3-nitro-1H-pyrazol-5-yl) methanol 22 (1.30 g, 0.52 mmol) in chloroform (50 mL), phosphorus tribromide (2.1 g, 0.78 mmol) was charged and refluxed for 2 hour. The reaction mixture was cooled to room temperature and basified with saturated sodium bicarbonate solution to pH 9. The aqueous layer was extracted with chloroform (2 x 100 mL). The combined organic extract was washed with water (3 x 30 mL). The organic layer was dried (Na2SO4), filtered and evaporated to obtain 1 -(2-bromoethyl)-5 -(bromomethyl)-3 -nitro- 1 H-pyrazole 23 (1.30 g, 81% yield) as yellow solid. ‘HNMR (400 MHz, DMSO-d6): ? 7.20 (s, 1H),4.86 (s, 2H), 4.71 (t, 2H), 3.93 (t, 2H).

References:

WO2015/25197,2015,A1 Location in patent:Paragraph 00087