Diisopropylethylamine → HCID 460961, compound

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Reaction Steps

The compound (2S,3S,5S)-2-[N-[(3-hydroxy-2-methylphenyl)carbonyl]amino]-5-[N-(tert-butyloxycarbonyl)amino]-1,6-diphenyl-3-hydroxy hexane (RS-208) was prepared from RS-216. A solution of (2S,3S,5S)-2-amino-5-[N-(tert-butyloxycarbonyl)amino]-1,6-diphenyl-3-hydroxy hexane (RS-216, 1.1 g, 2.86 mmol), 3-hydroxy-2-methyl-benzoic acid (0.478 g, 3.2 mmol), O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU, 1.02 g, 3.2 mmol), 1-hydroxybenzotriazole hydrate (HOBT, 0.919 g, 6.0 mmol) and diisopropylethylamine (DIPEA, 103 ml, 6.0 mmol) in dimethylformamide (DMF, 30 ml) was stirred at room temperature for 2 h. After addition of aminoethyl morpholine (50 ml) the solvents were removed under vacuum and the residue was diluted with ethyl acetate and washed sequentially with aqueous NaHCO3, aqueous KHSO4, brine, then dried on Na2SO4, and concentrated in vacuo. Solid was suspended in ethyl acetate, filtered and residue was washed with ethyl acetate. Crystallization from ethyl acetate:methanol:hexane (1:0.2:1.5) provided 1.4 g (94%) of white solid; mp=162°-163° C.; TLC [Rf =0.75 (ethyl acetate:hexane, 7:3)]; HPLC rt=19.5 min; MS m/z 519 (M+H)+ ; 1H NMR.

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