Phenyl chloroformate → 3-(1,2-Oxazol-3-yl)-1-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]urea

Participants

Reaction Steps

(4-Aminophenyl)boronic acid pinacol ester (1 g) was dissolved in dry THF (30 mL), sodium bicarbonate (576 mg) added followed by the dropwise addition of phenylchloroformate (0.575 mL). The mixture was stirred at RT for 1 hour then. 3-aminoisoxazole (0.506 mL) added and the reaction left to stir at 40° C. for 16 h. More 3-aminoisoxazole (0.506 mL) and sodium bicarbonate (576 mg) were added and the reaction heated to 75° C. for 8 h. before the mixture was concentrated in vacuo and partitioned between DCM (50 mL) and water (50 mL). The organic layer was dried over magnesium sulphate, filtered and vacuumed to dryness. The residue was chromatographed on silica, eluting with ethyl acetate, to give the desired compound (1.05 g) as a white solid.

Provenance & Evidence