Ethyl 3-{[(4-{[cyclohexyl(5-hydroxy-3-methyl-1-benzofuran-2-yl)methyl]amino}phenyl)carbonyl](methyl)amino}propanoate (0.23 g) synthesized in the above-mentioned (1) was dissolved in tetrahydrofuran (5 mL), and 2-pyridinemethanol (62 mg), tributylphosphine (0.21 mL) and 1,1′-(azodicarbonyl)dipiperidine (0.21 g) were added to the solution under ice-cooling. The ice bath was removed, the reaction mixture was stirred at room temperature for 12 hr, then hexane (15 mL) was added to the mixture, and the precipitate was filtered off through celite. Water was added to the filtrate, and the mixture was extracted with ethyl acetate. The extract was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:1, volume ratio) to give the title object compound (0.19 g, 70%) as a pale-yellow oil.
