反应详情

(3R,4R,5R)-3-Amino-4,5-dimethyl-octanoic acid hydrochloride (92 g, 0.41 mol) was dissolved in 250 mL to 260 mL of dry MeOH in a 2 L 3-necked round bottom flask. To this solution was added Et3N (0.45 mol, 45.8 g) dropwise, which formed a white precipitate. The resulting slurry was stirred at room temperature for 15 minutes. The solvent was removed to dryness. The white solid was dispersed in 1 L of CH2Cl2 (1 L) and stirred for 1 hour. CH3CN (0.6 L) was added, and the slurry was stirred for another 0.5 hours. The slurry was filtered and the solids were washed 2× with 50 mL aliquots of CH3CN, giving 71 g of the titled compound as a white solid (92% yield; 98.8% chiral purity; 99.7% chemical purity): 1H NMR (400 MHz, CD3OD): 0.89 (t, J=7.2 Hz, 3 H), 0.91 (d, J=5.1 Hz, 3 H), 0.93 (d, J=6.6 Hz, 3 H), 1.02–1.65 (m, 4 H), 2.26 (dd, J=10.2 Hz, 1 H), 2.50 (dd, J=3.7 Hz, 1 H), 3.27 (m, J=1.6 Hz, 2 H) 3.33–3.28 (m, 1 H), 4.82 (s, 3 H).

1. customwhich formed a white precipitate
2. customThe solvent was removed to dryness
3. additionThe white solid was dispersed in 1 L of CH2Cl2 (1 L)
4. stirringstirred for 1 hour
5. additionCH3CN (0.6 L) was added
6. stirringthe slurry was stirred for another 0.5 hours
7. filtrationThe slurry was filtered
8. washthe solids were washed 2× with 50 mL aliquots of CH3CN