反应详情

To a solution of (R)-2-(((benzyloxy)carbonyl)(methyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid (1.40 g, 3.98 mmol) in MeOH (18.79 ml) was added 10% Pd/C (0.424 g, 0.398 mmol) and the reaction mixture was placed under a hydrogen atmosphere using. The reaction was allowed to stir at room temperature for 18 h. The catalyst was removed by filtration on CELITE® and the filtrate was concentrated under reduced pressure to give a white solid. The crude material was dissolved in Acetonitrile (9.40 ml), Water (9.40 ml) and TEA (1.111 mL, 7.97 mmol). The solution was cooled to 0° C. using and icebath and the FMOC-OSU (1.344 g, 3.98 mmol) was added. The reaction mixture was allowed to stir while warming up to room temperature for 18 hours. The crude product was diluted in 200 mL EtOAc and washed with 1N HCl aqueous solution and brine. The organic phase was dried over anhydrous sodium sulfate. After filtration and concentration a clear oil was obtained, which was purified by silica gel chromatography using 100% hexanes to 100% EtOAc. (R)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)(methyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid was obtained as a colorless oil (0.481 g, 28%). 1H NMR (400 MHz, chloroform-d) δ 7.81-7.68 (m, 2H), 7.63-7.49 (m, 2H), 7.43-7.21 (m, 4H), 5.95 (br. s., 3H), 4.76 (dd, J=10.7, 4.5 Hz, 1H), 4.60-4.48 (m, 1H), 4.47-4.32 (m, 2H), 4.29-4.10 (m, 1H), 2.87 (s, 3H), 2.43-1.82 (m, 4H), 1.51-1.36 (m, 9H).

1. customThe catalyst was removed by filtration on CELITE®
2. concentrationthe filtrate was concentrated under reduced pressure
3. customto give a white solid
4. temperatureThe solution was cooled to 0° C.
5. stirringto stir
6. temperaturewhile warming up to room temperature for 18 hours
7. washwashed with 1N HCl aqueous solution and brine
8. dry with materialThe organic phase was dried over anhydrous sodium sulfate
9. filtrationAfter filtration and concentration a clear oil
10. customwas obtained
11. customwhich was purified by silica gel chromatography