Triphenylphosphine → ethyl 1-{2-[(tert-butoxycarbonyl)amino]ethyl}-3-{[tert-butyl(dimethyl)silyl]oxy}-1H-pyrazole-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

Di-tert-butyl azodicarboxylate (1.07 g, 4.66 mmol) was added to a stirred solution of triphenylphosphine (1.22 g, 4.66 mmol), tert-butyl N-(2-hydroxyethyl)carbamate (0.8 mL, 5.18 mmol) and ethyl 5-{[tert-butyl(dimethyl)silyl]oxy}-1H-pyrazole-3-carboxylate (0.7 g, 2.59 mmol) in THF (22 mL). The mixture was stirred at 80° C. for 16 hours and the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography (silica; AcOEt in heptane 0/100 to 30/70). The desired fractions were collected and the solvents evaporated in vacuo to yield ethyl 1-{2-[(tert-butoxycarbonyl)amino]ethyl}-3-{[tert-butyl(dimethyl)silyl]oxy}-1H-pyrazole-5-carboxylate (1.01 g, 94% yield) as a white solid.

Provenance & Evidence