To a suspension of 2-(pyridin-2-ylamino)-thiazole-5-carbaldehyde (1.0 g, 4.90 mmol, compound 1A) in methylene chloride (20 mL) at RT 3-amino-4-fluorobenzoic acid (0.95 g, 4.90 mmol) TFA (5 mL) and triethylsilane (1.71 mg, 14.7 mmol) were added. The above reaction mixture was stirred at RT for 4 h, then concentrated in vacuo and the resulting slurry was triturated with methanol to afford 4-fluoro-3-{[2-(pyridin-2-ylamino)-thiazol-5-ylmethyl]-amino}-benzoic acid as light yellow solid (1.54 g, 91%) (M+H)+=345.
