M-Cresol → Nalpha-(5-(N-2-picolylaminomethyl)thiophene-2-carbonyl)-L-ornithine

A mixed solution of trifluoroacetic acid (1.4 ml), thioanisole (0.36 ml), and m-cresol (0.32 ml) was added to the compound obtained in Example 14-3 (56.2 mg). After 1.5 hours, the reaction solution was concentrated. Methanol was added to the residue and the mixture was washed with hexane. The methanol layer was concentrated and the residue was crude-purified by silica gel column chromatography (3 g, chloroform/methanol/water=7/3/0.5) to obtain the title compound (18.2 mg) as colorless syrup.