Then, the resulting lithium salt of 2-amino-5-nitro-nicotinic acid, C-(5-phenoxy-thiophen-2-yl)-methylamine (60 mg, 0.29 mmol), benzotriazol-1-yl-tris(dimethylamino)phosphonium hexafluorophosphate (162 mg, 0.367 mmol) and triethylamine (103 μl, 0.735 mmol) were dissolved in N,N-dimethylformamide (2.0 mL), and the solution was stirred for 6 hours at room temperature. Water was added to the reaction solution, which was then extracted with ethyl acetate, and the organic layer was washed with water and brine. The solvent was evaporated in vacuo, the residue was purified by silica gel column chromatography (hexane:ethyl acetate=1:1), and the title compound (87 mg, 0.24 mmol, 96%) was obtained as a pale yellow solid.
