反应详情

To a mixture of PPh3 (4.19 g, 16 mmol) and imidazole (1.09 g, 16 mmol) in anhydrous CH2Cl2 (40 mL) was added slowly iodine (4.07 g, 16 mmol) at rt. After 5 min, a solution of (2S)-2-[[(1,1-dimethylethoxy)carbonyl]amino]-4-hydroxy-butanoic acid phenylmethyl ester (4.12 g, 13.3 mmol) in CH2Cl2 (20 mL) was added at 0° C. After 2 h at rt, the reaction mixture was filtered through a short silica gel column. The filtrate was concentrated in vacuo, and the resulting residue was purified by flash chromatography (hexane-EtOAc, 95:5 to 9:1) to afford the product as light yellow oil (3.22 g, 58%). 1H NMR (CDCl3) δ 1.43 (s, 9H), 2.20 (m, 1H), 2.40 (m, 1H), 3.13 (m, 2H), 4.35 (br.s, 1H), 5.10 (br.s, 1H), 5.20 (AB, 2H), 7.30–7.40 (m, 5H). LC-MS: 420 (M++1).

1. waitAfter 2 h at rt
2. filtrationthe reaction mixture was filtered through a short silica gel column
3. concentrationThe filtrate was concentrated in vacuo
4. customthe resulting residue was purified by flash chromatography (hexane-EtOAc, 95:5 to 9:1)