反应详情

To a precooled (<−10° C. internal temperature) solution of 1.6M n-butyl lithium in hexanes (100 ml) in anhydrous diethyl ether (100 ml) under argon was added a solution of 4-bromo-1-methyl-1H-pyrazole (23.42 g) from Example 111 in diethyl ether (50 ml) at a rate to maintain the temperature. The reaction was allowed to stir for a further 20 minutes before tributyltin chloride (43.4 ml) was added in diethyl ether (50 ml). The reaction temperature was allowed to rise to 20° C. The reaction was diluted with diethyl ether and the insoluble material removed by suction filtration. Evaporation of the solvent in vacuo afforded 56 g of the title compound as an oil. MS, m/z: 373 [M+H]+. Residual amounts of tin residues were removed from the oil by distillation using a kugelrohr apparatus under high vacuum at 170° C.

1. temperatureto maintain the temperature
2. customto rise to 20° C
3. customthe insoluble material removed by suction filtration
4. customEvaporation of the solvent in vacuo