(E)-(R)-4-tert-butoxycarbonylamino-2-methyl-pent-2-enoic acid ethyl ester → (2R,4R)-4-tert-butoxycarbonylamino-2-methyl-pentanoic acid ethyl ester

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Reaction Steps

Next, a solution of (E)-(R)-4-tert-butoxycarbonylamino-2-methyl-pent-2-enoic acid ethyl ester (1.83 g, 7.11 mmol) in ethyl acetate (75 mL) is hydrogenated over 10% Pt/C (183 mg) at 1 atm for 18 hours. The catalyst is filtered through Celite and the solvent is removed under reduced pressure. The residue is purified by chiral HPLC to afford (2R,4R)-4-tert-butoxycarbonylamino-2-methyl-pentanoic acid ethyl ester, 1H-NMR (400 MHz, CDCl3); 6 ppm 1.13 (t, 3H), 1.18 (m, 3H), 1.26 (t, 3H), 1.43 (s, 9H), 1.81 (s, 1H), 2.50 (m, 1H), 3.72 (m broad, 1H), 4.14 (m, 2H), 4.33 (m broad, 1H).

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