Benzyl bromoacetate → HCID 22861554, compound

Participants

Reaction Steps

3{1,4-Dioxo-4-(phenylmethoxy)-2(R) -{[1-(triphenylmethyl)-1H-imidazol-4-yl]methyl}butyl}-4(S)-(1-methylethyl)-2-oxazolidinone: A 1.0M solution of sodium bis(trimethylsilyl)amide (18.0 mL, 18.0 mmol, Aldrich Chemical Co., Inc., Milwaukee, Wis., USA) was added dropwise (18 min) to a cold (-78°) solution of the product of the preceding section (8.06 g, 16.3 mmol) in THF (65 mL). After 40 min at -78°, to a solution of benzyl 2-bromoacetate (7.48 g, 32.7 mmol) in THF (2 mL) was added dropwise to the solution. The reaction mixture was stirred at -78°for 1.5 h, quenched with an aqueous saturated solution of NH4Cl, allowed to warm to room temperature and then poured into a mixture of H2O (500 mL) and aqueous saturated solution of NH4Cl (100 mL). The resulting mixture was extracted with EtOAc. The EtOAc extract was washed with a saturated aqueous solution of NaHCO3 and then brine, dried (MgSO4) and concentrated under reduced pressure to give 3-{1,4-dioxo-4-(phenylmethoxy)-2-{[1-(triphenylmethyl)-1H-imidazol-4-yl]methyl}butyl}-4(S)-(1-methylethyl)-2-oxazolidinone as a mixture of 2(R)- and 2(S)-epimers in a 8 to 1 ratio by weight. Separation of the epimers by flash chromatography (SiO2, eluent: hexane-EtOAc, 1:2) yielded the desired 2(R)-epimer (Rf=0.25, eluent: hexane-EtOAc,1:2). The 1H NMR (CDCl3) of the 2(R)-epimer showed δ7.34-7.28 (m, 15H), 7.13-7.08 (m, 6H), 6.59 (d, J=1.3 Hz, 1H), 5.06 (s,2H), 4.55-4.45 (m, 1H), 4.38 (td, J=3.9 Hz,5.4 Hz, 1H), 4.15-4.10 (m,2H), 2.97 (dd, J=10.3 Hz,16.9 Hz, 1H), 2.88 (dd, J=6.3 Hz,14.3 Hz, 1H), 2.73 (dd, J=7.0 Hz,14.3 Hz, 1H), 2.59 (dd, J=4.4 Hz,16.9 Hz, 1H), 2.32 (hept d, J=3.9 Hz,7.0 Hz, 1H), 0.87 (d, J=7.1 Hz, 3H), 0.85 (d, J=6.8 Hz, 3H).

Provenance & Evidence