(R)-aminocarnitine (20 mg, 0.12 mmol) and 2,5-dioxopyrrolidin-1-yl 4-(3-methylfuran-2-carboxamido)benzoate (82 mg, 0.24 mmol) were dissolved into DMF (1 mL). Triethylamine (50 μL, 0.36 mmol) was added and the solution was stirred at room temperature for 48 h. Diethyl ether (20 mL) was added and a white precipitate was collected. The powder was purified by silica gel chromatography (elution 10% MeOH/CH2Cl2 to 80% MeOH/CH2Cl2) to give the title compound as a white solid (20 mg, 43%). 1H NMR (400 MHz, D2O) δ 7.62 (d, 1H, J=1.4 Hz), 7.32-7.30 (m, 1H), 7.27-7.16 (m, 3H), 6.55 (d, 1H, J=1.8 Hz), 4.90-4.80 (m, 1H), 3.63-3.42 (m, 2H), 3.13 (s, 9H), 2.48-2.45 (m, 2H), 2.10 (s, 3H); MS ESI 388.2 [M+H]+, calcd for [C20H25N3O5+H]+ 388.18.
