4-[(4-Isopropyl-1,3-thiazol-2-yl)methoxy]-2-pyridinecarboxylic acid (50 mg, 0.18 mmol) was added with toluene (12 ml), triethylamine (63 pl, 0.45 mmol) and diphenyl phosphorylazide (78 μl, 0.36 mmol) and refluxed by heating at 140° C. for 7 hours. The reaction solution was returned to room temperature, added with tert-butanol (12 ml) and refluxed again by heating at 140° C. The reaction solution was stirred for 18 hours and then returned to room temperature, and the solvent was evaporated under reduced pressure. The residue was purified by thin layer silica gel chromatography (chloroform:methanol=40:1) to obtain 33 mg (53%) of the title compound.
