Iodoethane → (R)-5-biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylenepentanoic acid

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Reaction Steps

30 g (R)-5-Biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylenepentanoic acid (2-a, R1=Boc, R2=H, R3=CO2H), prepared according to Example 33 is added to 38.4 g caseium carbonate. Dimethylformamide (50 ml) is then added. Ethyl iodide (8.26 ml) is then added and the mixture is stirred for 16 h at room temperature. Water (1200 ml) and isopropyl acetate (120 ml) are added. The phases are separated. The aqueous phase is washed with isopropyl acetate (2×120 ml). The combined organic phases are washed with 20% aqueous sodium chloride solution (180 ml) and then dried (MgSO4). The mixture is concentrated under reduced pressure to afford (R)-5-biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylenepentanoic acid ethyl ester (2-a, R1=Boc, R2=H, R3=CO2Et). 1H NMR (CDCl3): 1.31 (3H), 1.40 (9H), 2.37 (1H), 2.59 (1H), 2.84 (1H), 2.93 (1H), 4.06 (1H), 4.24 (2H), 4.56 (1H), 5.62 (1H), 6.25 (1H), 7.29 (2H), 7.35 (1H), 7.45 (2H), 7.54 (2H), 7.59 (2H).

Provenance & Evidence