To a solution of methyl 5-(3,4,5,6-tetramethoxy-2-methylbenzyl)-2-(trifluoromethanesulfonyl)oxybenzoate (1.43 g, 2.8149 mmol) in toluene (32 ml) were added tetrakistriphenylphosphine palladium (98 mg, 0.0848 mmol), aqueous solution of sodium carbonate (2M aqueous solution, 3.66 ml), lithium chloride (239 mg, 5.6381 mmol) and ethanolic solution (5.9 ml) of pyridine-3-boronic acid 1,3-propanediol cyclic ester (684 mg, 4.2222 mmol) and the mixture was heated with stirring at 95° C. for 16 hours. The reaction solution was diluted with ethyl acetate (200 ml), washed with water and dried and the solvent was evaporated therefrom. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=1:1) to give the title compound (1.20 g, 2.7459 mmol, 98%).
