Cesium carbonate → 1-(oxan-4-yl)-1H-pyrazole-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A vial was charged with ethyl-1H-pyrazole-3-carboxylate (3.74 g, 26.7 mmol), the crude methanesulfonic acid tetrahydro-pyran-4-yl ester (29.4 mmol), Cs2CO3 (17.4 g, 53.4 mmol), and DMF (100 mL). The reaction mixture was heated to 80° C. and stirred overnight. The reaction was then partitioned between CH2Cl2 (250 mL) and water (250 mL), and the organic layer was washed with water (5×250 mL), dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude product containing 2 regioisomers was purified via flash chromatography on silica gel (95:5-50:50 hexanes:EtOAc) and the later eluting isomer was isolated. This was purified on silica gel a second time (85:15-60:40 hexanes:EtOAc) to give the pure desired product (1.14 g, 19%).

Provenance & Evidence