Reaction Steps
In a dry flask (3S,4R)-4-amino-3-[(S)-3-(4-fluoro-benzyl)-piperidine-1-carbonyl]-piperidine-1-carboxylic acid t-butyl ester (43 mg, 0.10 mmol) was dissolved in tetrahydrofuran (2 mL) and then triethylamine (19 μL, 0.14 mmol) and 3-acetylphenylisocyanate (17 μL, 0.12 mmol) were added. After stirring for 18 hours, removed half of the reaction mixture for purification. The remainder of the reaction mixture was taken onto the next reaction without purification. The aliquot was purified by preparative reverse-phase HPLC (10-80% acetonitrile in water with 0.05% trifluoroacetic acid) to give a white amorphous solid (17 mg, 57%). 1H NMR (400 MHz, DMSO-d6, 120° C.), δ: 8.64 (s, 1H), 7.94 (m, 1H), 7.57 (d, J=8, 1H), 7.46 (d, J=8, 1H), 7.33 (t, J=8, 1H), 7.17 (m, 2H), 7.00 (t, J=9, 2H), 6.13 (d, J=8, 1H), 4.07 (m, 1H), 3.87 (m, 1H), 3.61 (m, 1H), 3.42 (dd, J=14, J′=4, 1H), 3.32 (m, 1H), 2.98 (m, 2H), 2.70 (m, 1H), 2.50 (m, 1H), 2.49 (s, 3H), 2.02 (m, 1H), 1.73 (m, 3H), 1.53 (m, 1H), 1.39 (s, 9H), 1.22 (m, 2H). HRMS (ESI), C32H42FN4O5 m+/z: calc.=581.3139, found=581.3149.
