A ketone compound (408 mg) was prepared in substantially the same manner as in step b) of Synthesis Example 1, except that 430 mg of 7-[(5-methylthiopyridin-3-yl)hydroxymethyl]imidazo[5,1-b]thiazole and 320 mg of manganese dioxide were used as the starting compounds. 7-(5-Methylthiopyridin-3-yl)carbonyl-2-(tri-n-butylstannyl)imidazo[5,1-b]thiazole (179 mg) was prepared in substantially the same manner as in step c) of Synthesis Example 1, except that 138 mg of the ketone compound, 0.300 ml of tri-n-butylstannyl chloride, and 2.25 ml of a 1.0 N lithium bis(trimethylsilyl)amide/THF solution were used as the starting materials.
