2-Bromoethanol → ethyl 1-(2-bromoethyl)-3-(phenoxymethyl)-1H-pyrazole-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

Di-tert-butyl azodicarboxylate (1.68 g, 7.30 mmol) was added portionwise to a stirred solution of 5-phenoxymethyl-2H-pyrazole-3-carboxylic acid ethyl ester (1.0 g, 4.06 mmol), 2-bromoethanol (0.58 mL, 8.12 mmol) and triphenylphosphine (1.92 g, 7.30 mmol) in THF (24.5 mL) at 0° C. The mixture was stirred at 120° C. for 30 minutes under microwave irradiation and then the solvent was evaporated in vacuo. The crude product was purified by flash column chromatography (silica; DCM). The desired fractions were collected and concentrated in vacuo to yield 2-(2-bromoethyl)-5-phenoxymethyl-2H-pyrazole-3-carboxylic acid ethyl ester (1.08 g, 71% yield) as a yellow oil.

Provenance & Evidence