ethyl 2-[6-(2,6-difluorophenyl)-4-oxo-5-aza-3-oxahex-5-yl]-5-{4-[(3-{[(4-{5-[6-(2,6-difluorophenyl)-4-oxo-5-aza-3-oxahex-5-yl]-3-[(dimethylamino)methyl]-4-(ethoxycarbonyl)thiophen-2-yl}phenyl)amino]carbonyl}-4-oxo-3-aza-2-oxabut-4-yl)amino]phenyl}-4-[(dimethylamino)methyl]thiophene-3-carboxylate