Diisopropylethylamine → N-[(1S, 2S)-1-(benzyloxycarbonylamino-methyl)-2-hydroxy-pent-3-ynyl]-malonamic acid benzyl ester

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Reaction Steps

The compound [(2S,3S)-2-amino-3-hydroxy-hex-4-ynyl]-carbamic acid benzyl ester (1.45 g, 3.8 mmol, prepared as described in WO PCT 0250019) was dissolved in 38 mL of 1:1 CH2Cl2/DMF. The resultant solution was charged sequentially with mono-benzyl malonate (745 mg, 3.8 mmol), N,N-diisopropylethylamine (6.7 mL, 38 mmol) and HATU (1.75 g, 4.6 mmol). The mixture was stirred for 12 h at RT, concentrated in vacuo, and partitioned between EtOAc and sat. NH4Cl. The aqueous phase was extracted with EtOAc (1×). The combined organic extracts were washed with sat. NaHCO3 and brine, dried (Na2SO4), filtered, and concentrated in vacuo. The residue was purified by flash chromatography to provide N-[(1S,2S)-1-(benzyloxycarbonylamino-methyl)-2-hydroxy-pent-3-ynyl]-malonamic acid benzyl ester (1.5 g, 91% yield). MS found: (M+H)+=439.4. The entirity of this material was dissolved in THF (18 mL). This solution was charged sequentially with MeOH (6 mL) and aq. LiOH (84 mg LiOH in 6 mL water) and stirred for 12 h at RT. The mixture was concentrated in vacuo, and the residue was lyopholized from 1:1 acetonitrile/water to provide the lithium salt of N-[(1S,2S)-1-(benzyloxycarbonylamino-methyl)-2-hydroxy-pent-3-ynyl]-malonamic acid. MS found: (M+H)+=355.3.

Provenance & Evidence