反应详情

L-aspartic acid (4 g, 0.03 mol) was added to a Parr bottle containing a solution of sodium bicarbonate (5.04 g, 0.06 mol) in water (50 mL) to form a clear solution, with effervescence. A solution of 3,3-dimethylbutyraldehyde (3 g, 0.03 mol) in methanol (50 mL) was then added to the Parr bottle, followed by Pd/C (4% palladium on carbon, 50% wet, 0.4 g). The mixture was hydrogenated at 50 psi/room temperature for 2 days. If the reaction was not complete, fresh Pd/C (0.2 g) would be added and hydrogenation continued for an additional 8 hrs. The mixture was filtered through a Celite® bed, and the bed was washed with methanol (20 mL). The filtrate and washings were combined and concentrated under reduced pressure at 40-50° C. The pH of the remaining aqueous solution was adjusted to 3 with concentrated hydrochloric acid. The precipitated solid was filtered and dried in a vacuum oven at 50° C. for 4 hrs to give 4.75 g (73%) of crude N-neohexyl-L-aspartic acid. The crude product was slurried with aqueous ethanol (47.5, 80% ethanol, 20% water) for 15 minutes and filtered to give 3.3 g (51%) of >98% pure N-neohexyl-L-aspartic acid. M.P. 184-186° C.; [α]D +12.35 (c=1, water); NMR (D2O) δ3.37(t, 3H); 2.25-2.65 (m, 4H); 1.27-1.47 (m, 2H); 0.89(s, 9H); Anal. Calc'd. for C10H19NO4 ; C, 55.28; H, 8.81; N, 6.45; Found: C, 55.35; H, 8.86; N, 6.50.

1. customto form a clear solution
2. waithydrogenation continued for an additional 8 hrs
3. filtrationThe mixture was filtered through a Celite® bed
4. washthe bed was washed with methanol (20 mL)
5. concentrationconcentrated under reduced pressure at 40-50° C
6. filtrationThe precipitated solid was filtered
7. customdried in a vacuum oven at 50° C. for 4 hrs