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

Participants

Reaction Conditions

Reaction Steps

To a solution of 3-tert-butyl-1-p-tolyl-1H-pyrazol-5-amine (4) (WO 2000043384) (1.00 g, 4.36 mmol) in DCM (90 mL) was added a saturated aq solution of NaHCO3 (60 mL). The mixture was stirred vigorously, cooled to 0° C. and diphosgene (2.1 mL, 17.4 mmol) was added in a single portion. After stirring for 1 hr at RT, the layers were separated and the organics dried and evaporated to give a brown oil. The oil was triturated with iso-hexane (5.0 mL) and the solid filtered. The filtrate was concentrated in vacuo to give 3-tert-butyl-5-isocyanato-1-p-tolyl-1H-pyrazole (19) as a light brown oil (1.00 g, 3.92 mmol, 90%). m/z 288 (in MeOH) (M+H+MeOH)+ (ES+).

Provenance & Evidence