(R)-aminocarnitine (16 mg, 0.1 mmol) and 2,5-dioxopyrrolidin-1-yl 5-(phenylethynyl)furan-2-carboxylate (60 mg, 0.19 mmol) were dissolved into DMF (1 mL). Triethylamine (50 μL, 0.36 mmol) was added and the solution was stirred at room temperature for 18 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 100% MeOH) to give the title compound as a white powder (10 mg, 24%). 1H NMR (400 MHz, D2O) δ 7.35-7.33 (m, 2H), 7.25-7.16 (m, 3H), 7.02 (d, 1H, J=3.7 Hz), 6.58 (d, 1H, J=3.6 Hz), 4.90-4.80 (m, 1H), 3.63-3.55 (m, 1H), 3.47-3.42 (m, 1H), 3.04 (s, 9H), 2.51-2.41 (m, 2H); MS ESI 355.1 [M+H]+, calcd for [C20H22N2O4+H]+ 355.16.
