At 0℃, triethylamine (4ml, 0.03mol, 3eq.) and di-tert-butyl dicarbonate (2.1g, 0.01mol, 1eq.) were added to a 5ml acetonitrile solution of compound i-1a (1.5g, 0.01mol, 1eq.). After reacting at room temperature for 5h, the organic phase was extracted with water and concentrated. The target compound i-1b (yield 95%) was obtained by silica gel column chromatography.
Triphenylphosphine (9.0 g, 0.03 mol, 1.5 eq.) and imidazole (2.3 g, 0.03 mol, 1.5 eq.) were dissolved in 100 ml of dry dichloromethane. Iodine (8.7 g, 0.03 mol, 2 eq.) was added to the reaction solution at 0 °C and stirred for 45 min. Compound i-1b (5 g, 0.02 mol, 1 eq.) was added in portions to the reaction solution. After stirring at room temperature for 2 h, the reaction was quenched with acetic acid (0.2 ml) and sodium thiosulfate aqueous solution. The organic phase was extracted and concentrated, and the target compound i-1c, namely BOC-3-iodo-D-alanine methyl ester (90% yield), was obtained by silica gel column chromatography.
