To a solution of 4-amino-3-fluorobenzoic acid (0.883 g, 5.69 mmol), N-tert-butyl-5-(piperazin-1-ylmethyl)furan-2-carboxamide (1.51 g, 5.69 mmol) and triethyl-amine (0.576 g, 5.69 mmol, 0.791 mL) in dichloromethane was added 1-propanephosphonic acid cyclic anhydride (3.62 g, 5.69 mmol, 3.39 mL, 50% solution in ethyl acetate). The reaction was stirred for 2 hours then concentrated under reduced pressure. The residue was taken up in ethyl acetate, washed with sodium bicarbonate, water and brine. The organic phase was concentrated under reduced pressure to give the title compound (0.93 g). MS (ESI) m/z 403.6 [M+H]+
