3-bromo-N-methoxy-N,2-dimethylbenzamide → 1-(3-Bromo-2-methylphenyl)-1-pentanone

To a solution of 3-bromo-N,2-dimethyl-N-(methyloxy)benzamide (2.55 g, 9.88 mmol) in anhydrous THF (28 mL) under nitrogen at −78° C. was added a butylmagnesium chloride (20% wt in THF/toluene, 6.94 mL, 11.90 mmol) drop-wise over 15 min. The resulting solution was stirred at −78° C. for 1 h, was allowed to warm to 0° C. and then stirred with slow warming to ambient temperature over 20 h. The reaction was then quenched with water (50 mL) and extracted with EtOAc (2×60 mL). Some saturated aqueous NH4Cl was added to disperse the emulsion formed. The resulting organic layer was then washed with brine (100 mL), dried (Na2SO4), filtered and reduced under vacuum. Purification by SPE (silica, 50 g cartridge), eluting with cyclohexane:EtOAc (gradient 49:1 to 9:1) afforded the title compound as a colourless oil (706 mg).