Acetic Acid → 4-(Benzo[b]thiophen-2-yl)-5-bromo-2-chloropyrimidine

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Reaction Conditions

Reaction Steps

n-Butyl lithium (20.7 mL, 1.6 M in hexane) is added dropwise to a stirred solution of benzo[b]thiophene (4.12 g, 30.1 mmol) in anhydrous THF (50 mL) at −78° C. under nitrogen. The resultant solution is allowed to stir at −78° C. for 15 minutes. The lithiated benzo[b]thiophene is then added via canula over 20 minutes to a stirred solution of 5-bromo-2-chloro-pyrimidine (5.95 g, 30.1 mmol) in anhydrous THF (100 mL) at −30° C. Upon the completion of the addition, the solution is allowed to stir at −30° C. for an additional 30 minutes then at 0° C. for another 30 minutes. The reaction is quenched with acetic acid (1.99 g, 33.1 mmol), then after 5 minutes, it is treated with a solution of DDQ (7.17 g, 31.6 mmol) in anhydrous THF (150 mL) in portions at 10° C. The mixture is stirred for 20 minutes at 10° C. before it is concentrated to give a dark solid. The solid is then suspended in chloroform (500 mL) and the suspension is sonicated and filtered through a pad of silica. Additional 700 mL chloroform is used to wash the solid. The combined filtrates are concentrated to give a solid. The solid is re-suspended in dichloromethane (20 mL)/diethyl ether (20 mL) and the suspension is sonicated and filtered to give the title compound as a yellowish solid (9.62 g, 98% yield).

Provenance & Evidence