Diisopropylethylamine → (2r,4s)-5-Biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpentanoic acid diisopropylethylammonium salt

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Reaction Steps

1 g (2R,4S)-5-Biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpentanoic acid (1-a, R1=Boc, R2=H, R3=CO2H) is added to ethanol (10 ml). Diisopropylethylamine (0.454 ml) is then added and the mixture is stirred at room temperature for 30 minutes. The mixture is then concentrated in vacuo to afford (2R,4S)-5-biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpentanoic acid diisopropylethylammonium salt (1-a, R1=Boc, R2=H, R3=CO2− [NHiPr2Et]+). 1H NMR (DMSO-d6): 0.95-0.98 (15 H), 1.04 (3H), 1.32 (9H), 1.36 (1H), 1.74 (1H), 2.38-2.49 (3 H), 2.67 (2H), 2.99 (2H), 3.66 (1H), 6.29 and 6.70 (1H), 7.23-7.25 (2H), 7.33-7.37 (1H), 7.42-7.46 (2H), 7.55-7.57 (2H), 7.62-7.64 (2H).

Provenance & Evidence