To a stirred solution of 6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinic acid (500 mg, 1.6 mmol), N-ethyldiisopropylamine (1.04 g, 2.0 mmol) and 1-hydroxybenzotriazole hydrate (40 mg, 0.3 mmol) in DMF (16 mL) at ambient temperature and under argon was added 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (517 mg, 1.6 mmol) followed by N-hydroxymethylacetamidine (149 mg, 2.0 mmol). After 14 h the mixture was diluted with water (15 mL) and extracted with EtOAc (3×25 mL). The combined extracts were washed with 10% aqueous LiCl solution (2×10 mL) then dried over sodium sulfate, filtered and concentrated. The residue was then dissolved in DMF (16 mL) and heated at 140° C. for 3 h then cooled, diluted with EtOAc (60 mL), washed with 10% aqueous LiCl (3×100 mL), then dried over sodium sulfate, filtered and concentrated. Purification by chromatography (SiO2, heptane:ethyl acetate 8:2 to 0:1) afforded the title compound (385 mg, 69%) as a yellow solid. MS: m/e=349.4 [M+H]+.
