tert-butyl bromoacetate (13 ml, 80 mmol) is added dropwise to a zinc suspension (5.3 g, 80 mmol activated with 6N HCl over 10 seconds, then washed successively with water until a neutral pH is achieved, with acetone and with diethyl ether) in anhydrous tetrahydrofuran (60 ml) under reflux. The reaction medium is maintained under reflux for another 10 minutes after the addition is terminated. Then, a solution of 1-{3-[(benzyloxy)methyl]-2-methoxy-4-pyridinyl}-1-propanone (5.8 g, 20 mmol) in anhydrous tetrahydrofuran (20 ml) is added and the reaction mixture is agitated under reflux for another hour. The reaction is stopped at 0° C. with saturated aqueous ammonium chloride (100 ml) and the reaction mixture is extracted with diethyl ether. The combined extracts are dried over sodium sulphate and evaporated, which produces a yellow oil which is purified by column chromatography (SiO2, TBMO/HX: 5/95 to 10/90) in order to obtain the tert-butyl ester (J) (7 g, 95%) in the form of a limpid liquid.
