p-Toluenesulfonic acid → 3-Allyloxycarbonylamino-4,4-diethoxy-butyric acid tert-butyl ester

反応式

[C:1]([O:5][C:6](=[O:18])[CH2:7][CH:8]([NH:11][C:12]([O:14][CH2:15][CH:16]=[CH2:17])=[O:13])[CH:9]=[O:10])([CH3:4])([CH3:3])[CH3:2].C([O-])([O-])[O:20][CH2:21][CH3:22].[C:25]1(C)C=CC(S(O)(=O)=O)=C[CH:26]=1>C(O)C>[C:1]([O:5][C:6](=[O:18])[CH2:7][CH:8]([NH:11][C:12]([O:14][CH2:15][CH:16]=[CH2:17])=[O:13])[CH:9]([O:20][CH2:21][CH3:22])[O:10][CH2:25][CH3:26])([CH3:3])([CH3:2])[CH3:4]

参加物

実験手順

To a solution of 3-allyloxycarbonylamino-4-oxo-butyric acid tert-butyl ester, 102, (13.3 g, 51.7 mmol) in anhydrous ethanol (75 mL) is added ethyl orthoformate (45 mL, 0.270 mol), p-toluenesulfonic acid (0.15 g, cat.) and 4 Å molecular sieves (10 g, kiln dried) under N2. After the consumption of starting material, the sieves are removed by filtration and the solvent removed in vacuo to provide the desired compound as a clear oil which is used directly without further purification. MS (ESI): m/e=332.21 (M+H).