Trifluoroacetic anhydride → 3-fluoro-6-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl)pyridin-2-yl acetate

Participants

Reaction Conditions

Reaction Steps

To a cold mixture of 3-(1-(2-fluorobenzyl)-3-(5-fluoropyridin-2-yl)-1H-pyrazol-5-yl)isoxazole (1 equiv.) and urea compound with hydrogen peroxide (1:1) (3 equiv.) in DCM (1.7 ml) at 0° C., was added trifluoroacetic anhydride (3 equiv.). The mixture was allowed to warm to 25° C. and stirred for 3 days. The mixture was quenched with saturated solution of sodium bisulfate and extracted with dichloromethane (50 ml×3). The organic layers were combined, filtered and evaporated to give solid. The solid was dissolved in acetic anhydride (1.4 ml) and heated to 145° C. for 4 h. The mixture was cooled to 25° C., diluted with dichloromethane (100 ml) and washed with saturated solution of sodium bicarbonate (50 ml). The organic layer was dried (MgSO4), filtered and evaporated to give an oil. Purification of the oil by column chromatography (0 to 30% ethyl acetate in hexanes) gave 3-fluoro-6-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl)pyridin-2-yl acetate as an yellow oil. The yellow oil was combined with methanol (1.7 ml) and potassium carbonate (1 equiv.). The mixture was heated to 65° C. for 30 min. The mixture was concentrated under vacuum. The resulting residue was diluted with dichloromethane (100 ml) and washed with 1N HCl (30 ml). The organic layer was dried (MgSO4), filtered and evaporated to give a solid. Purification of the solid by column chromatography (0 to 5% methanol in dichloromethane) gave 3-fluoro-6-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl)pyridin-2(1H)-one as a yellow solid (7% overall yield).

Provenance & Evidence