A solution of 13.1 g (120.8 mmol, 2.8 equiv) of benzyl alcohol in 35 ml of dry tetrahydrofuran is added dropwise over 10 minutes to a room temperature slurry of 4.3 g (107.5 mmol, 2.5 equiv) of 60% NaH oil dispersion in 65 ml of tetrahydrofuran under nitrogen atmosphere. The reaction is stirred for 15 minutes then cooled in an ice-water bath. A hot solution of 11.4 g (43.7 mmol) 3-chloro-5-methoxybenzo[b]thiophene-2-carbonylchloride (prepared by the method described by Sudabeh Pakray and Raymond N. Castle in J. Heterocyclic Chem., 1986, 23, 1571) in 95 ml of tetrahydrofuran is added rapidly to the 0° C. reaction mixture. The reaction is stirred at 0° C. for 15 minutes, warmed at reflux for three hours and allowed to cool to room temperature before pouring onto 700 g of ice-water. The resulting mixture is extracted with diethyl ether (4×200 ml). The combined extracts are washed with saturated aqueous NaHCO3 (100 ml), water (100 ml) and saturated aqueous NaCl, dried over Na2SO4 and concentrated in vacuo to give a brownish yellow solid. The material was used as is in the subsequent reaction. A sample of the residue is rccrystallized from ethanol-water to give analytically pure benzyl 3-benzyloxy-5-methoxybenzo[b]thiophene-2-carboxylate as a white crystalline solid: mp 66°-67° C.
