To obtain the subject new furan derivative which is a synthetic intermediate for 2-(3-cyanophenyl)thiazole derivative useful as a xanthineoxidase inhibitor.

This compound is represented by formula I (R1 is H or a 1-5C alkyl; X is a halogen, OH or a ≤7C alkanesulfonyloxy or cyano), e.g. 2, 3- dimethoxy-5-bromo-2,3-dihydrobenzo (b) furan. The compound of formula I is obtained by dissolving e.g. a dihydrobenzo(b)furan derivative of formula II (e.g. 2,3-dimethoxy-2,3-dihydrobenzofuran) in an acetonitrile-water mixed solvent, preferably together with sodium bromide and monosodium phosphate as supporting electrolytes and subjecting the compound to electrolytic halogenation reaction in 1-1,000 mA/cm2 and 2-40 F/mol electrification amount at 0-100°C.