Amine 2b (0.5 ml, 2 mmol) was dissolved in 20 ml of AcOEt and at 0° C. triphosgene (580 mg, 2 mmol) was added to the solution. The mixture was warmed at 80° C. for 4 hours then evaporated and the residue was dissolved in 5 ml of DMF. The solution of the isocyanate was added dropwise to a solution in DMF (10 ml) of compound 1a (296 mg, 1.99 mmol) and the mixture was warmed at 80° C. for 8 hours. (TLC AcOEt 9.5/MeOH 0.5). The solvent was evaporated and the crude was dissolved in AcOEt (30 ml) and washed with water (1×20 ml) and brine. The organic phase was dried over sodium sulfate and concentrated under vacuum. The purification of the crude residue by chromatographic column gave 170 mg of a yellow solid. Yield=20% 1HNMR (DMSO, 400 MHz) δ 1.91 (4H, bs), 3.22 (4H, bs), 4.38 (2H, d, J=5.2 Hz), 6.62 (1H, d, J=8 Hz), 6.72 (1H, t), 6.83 (1H, t), 6.95 (1H, d, J=8 Hz), 7.08 (1H, s), 7.18 (1H, d, J=7.6 Hz), 7.45 (1H, d, J=7.6 Hz), 8.35 (1H, bs), 9.98 (1H, bs), 10.60 (1H, bs); [M+1] 420.18 (C20H20F3N5O2 requires 419.4).
