Diphosgene → 3-tert-Butyl-5-isocyanato-1-p-tolyl-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A saturated aq. solution of NaHCO3 (14 mL) was added to a solution of 3-tert-butyl-1-p-tolyl-1H-pyrazol-5-amine (WO 2000043384) (206 mg, 0.900 mmol) in DCM (20 mL) and the mixture was cooled to 0° C. and stirred vigorously whilst trichloromethylchloroformate (325 μL, 2.70 mmol) was added in a single portion. The vigorous stirring was continued at 0° C. for a further 80 min. The organic layer was separated and dried and was then evaporated in vacuo to provide 3-tert-butyl-5-isocyanato-1-p-tolyl-1H-pyrazole, Intermediate B1 as orange oil. This material was pumped for 30 min under high vacuum and was then taken up into THF (6.0 mL) and kept under nitrogen at 0° C. and used directly in the next step.

Provenance & Evidence