3-Amino-6-chloro-pyridine-2-carboxylic acid (636 mg) was suspended in methanol (8 mL) and toluene (22 mL) was added. A solution of (trimethylmethylsilyl) diazomethane (2.0 M hexane solution, 2.4 mL) was slowly added to the reaction mixture. After stirring for 1 hour at room temperature, another portion of (trimethylmethylsilyl)diazomethane (550 l) was added and the mixture was stirred for another 45 minutes. The reaction mixture was quenched with water and extracted three times with ethyl acetate. The combined organic layers were washed with 2N hydrochloric acid, saturated bicarbonate solution and brine, dried over MgSO4 and concentrated in vacuum. The residue was purified by column chromatography (silica gel 60, chloroform/ethyl acetate 50:1) to give 365 mg of the title compound of formula as a yellow solid.
