Potassium Carbonate → Boc-alpha-methyl-DL-leucine

To a stirred solution of 2-amino-2,4-dimethylpentanoic acid (1 g, 6.89 mmol) in tetrahydrofuran (15 mL) and water (15 mL) was added K2CO3 (3.81 g, 27.5 mmol) and the reaction mixture was stirred at room temperature for 10 min. To the resultant mixture (BOC)2O (3.20 mL, 13.77 mmol) was added dropwise and the reaction mixture was allowed to stir at room temperature for 14 h. The reaction mixture was then concentrated under reduced pressure. The aqueous layer was washed with ethyl acetate (3×15 mL) and acidified with a saturated aqueous solution of citric acid (25 mL) then extracted with ethyl acetate (3×50 mL). The combined organic extracts were washed with water (2×15 mL), brine (20 mL), dried over sodium sulfate and concentrated under reduced pressure to afford 2-((tert-butoxycarbonyl)amino)-2,4-dimethylpentanoic acid (1.6 g, 6.89 mmol, quantitative yield) as a white solid. 1H NMR (400 MHz, CDCl3) δ 5.36 (bs, 1 H), 2.10 (m, 1 H), 1.77 (m, 2 H), 1.74-1.65 (m, 3 H), 1.59 (s, 9 H), 0.89 (m, 3 H), 0.94 (m, 3 H).

1. stirringto stir at room temperature for 14 h
2. concentrationThe reaction mixture was then concentrated under reduced pressure
3. washThe aqueous layer was washed with ethyl acetate (3×15 mL)
4. extractionthen extracted with ethyl acetate (3×50 mL)
5. washThe combined organic extracts were washed with water (2×15 mL), brine (20 mL)
6. dry with materialdried over sodium sulfate
7. concentrationconcentrated under reduced pressure

ORDレコード

ord-b89b60ee942d45dca9064e207c3cff14

出典データセット

uspto-grants-2014_04

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US08703953B2