Cesium carbonate → Isopropyl 2-((tert-butoxycarbonyl)amino)-5-oxo-4-(2,3,5-trifluorophenyl)hexanoate

Participants

Reaction Steps

To a solution of 2 (10.98 g, 33.7 mmol) in THF (50 mL) was added TEA (4.8 g, 47.4 mmol) in portions at 15-20° C. The mixture was stirred for 30 h. After the reaction was complete, the solution was concentrated to give crude 7. To a solution of 44 (6.3 g, 33.7 mmol) and Cs2CO3 (5.0 g, 15.3 mmol) in DMSO (35 mL) was added slowly crude 7 in DMSO (35 mL) over 30 min at 15-20° C. The mixture was stirred for 1 h. After the reaction was complete, the mixture was partitioned with water and MTBE (50 mL) and extracted twice by MTBE. The combined organic layer was dried over Na2SO4 and concentrated. The crude residual was further purified by flash chromatography on silica gel (5-10% EtOAc/PE) to 45 (8.4 g, 60% yield). 1H NMR (DMSO-d6, 400 MHz): δ 6.77 (d, 1H), 6.59 (d, 1H), 5.11 (m, 1H), 4.93-4.89 (m, 1H), 4.12 (s, 2H), 2.66 (d, 1H), 2.05-2.01 (d, 3H), 1.38 (m, 9H), 1.18-1.15 (m, 6H); MS (ESI) m/e [M+H]+: 418.18.

Provenance & Evidence