Solid 4-aminomethylbenzeneboronic acid hydrochloride (0.111 g, 0.59 mmol) was added to a solution of 17 (0.394 g, 0.37 mmol), sodium carbonate (175 mg, 1.654 mmol) and palladium tetrakis triphenylphosphine (28.0 mg, 0.024 mmol) in toluene (10 mL), ethanol (5 mL) and water (5 mL). The reaction mixture was allowed to stir overnight at 30° C. The following day the reaction mixture was heated for a further 3 hours at 70° C. The reaction mixture was then partitioned between ethyl acetate and water. The organic layer was washed with water and brine and dried over magnesium sulphate. Excess solvent was removed by rotary evaporation under reduced pressure and the resulting residue was subjected to flash column chromatography (silica gel; gradient elution EtOAc/hexane 2/98→15/85). Removal of excess eluent from selected fractions afforded the desired product (0.230 mg, 0.22 mmol, 61%).
