4-broMo-3-nitro-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazole synthesis

Yield:1235407-33-6 92.07%

Reaction Conditions:

with trifluoroacetic acid in toluene at 110; for 4 h;

Steps:

Synthesis of 4-bromo-3-nitro-l-(tetrahydro-2H-pyran-2-yl)-lH-pyrazole

To a stirred solution of 4-bromo-3 -nitro- lH-pyrazole (5 g, 26.17 mmol), 3, 4-dihydro-2H-pyran (2.41 g, 28.79 mmol) in toluene (50 mL) and TFA (0.289 g, 2.61 mmol) was added and stirred at 1 10 °C for 4 h. Progress of the reaction was monitored by TLC. Upon completion the reaction mixture was diluted with ethyl acetate and saturated sodium bicarbonate and organic layer separated. The combined organic layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude compound was purified by column chromatography to afford the title compound (6.62 g, 92.07%)

References:

WO2016/44666,2016,A1 Location in patent:Paragraph 0388; 0389