An efficient synthesis of 5-chloro-3-[4-(3-diethylaminopropoxy)benzoyl]-2-(4-methoxyphenyl)benzofuran (8), a potent $eta$-amyloid aggregation inhibitor, is described. 5-Chloro-2-(4-methoxyphenyl)benzofuran (3) was obtained by the one-pot synthesis of 4-chlorophenol with $omega$(methylsulfinyl)-p-methoxyacetophenone (1) under Pummerer reaction conditions, and it was followed by the desulfurization of the resultant 5-chloro-3-methylthio-2-(4-methoxyphenyl)benzofuran (2e). Acylation of benzofuran 3 with 4-(3-bromopropoxy)benzoyl chloride (6) gave the ketone 7, which was converted into compound 8 by the treatment of diethylamine.