Sodium Bicarbonate → (2S*,3R*)-3-hydroxy-4-methyl-2-[(4-phenylphenyl)-methoxy-carbonylamino]-pentanoic acid

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Reaction Steps

To a stirred diastereomeric mixture containing (2S*,3R*)-2-amino-3-hydroxy-4-methyl-pentanoic acid (0.156 g, 1.06 mmol) and NaHCO3 (0.09 g, 1.06 mmol) in H2O (5.0 mL), at rt, the isomeric mixture containing (4-phenylphenyl)-methyl-2-pyridyl carbonate and (4-phenylphenyl)-methyl-2-oxopyridine-1-carboxylate (1.4 g, 4.6 mmol) [prepared as for example 17, step 1] in THF (5.0 mL) was added. After 15 h at rt, the crude mixture was rotary evaporated to remove the organics and subsequently extracted with Et2O (3×10 mL). The aqueous phase was acidified with 2.0 M HCl solution to pH 2-3 and subsequently extracted with AcOEt (3×20 mL). The organic fraction was dried over Na2SO4, filtered and concentrated to dryness to afford the title compound (0.196 g, 52% over two steps), as a yellowish solid, which was used in the next step without further purification. MS (ESI) m/z: 375 [M−NH4]+; (ESI) m/z: 356 [M−H]−. 1H NMR (DMSO-d6) δ 0.82 (d, J=6.66 Hz, 3H), 0.92 (d, J=6.39 Hz, 3H), 1.54-1.70 (m, 1H), 3.51 (t, J=8.38 Hz, 1H), 4.20 (dd, J=2.88, 9.42 Hz, 1H), 4.63 (d, J=8.86 Hz, 1H), 5.11 (s, 2H), 6.94 (d, J=9.44 Hz, 1H), 7.37 (t, J=6.55 Hz, 1H), 7.44-7.52 (m, 4H), 7.63-7.75 (m, 4H), 12.57 (s, 1H).

Provenance & Evidence