[CH3:1][C:2]([Si:5]([CH3:26])([CH3:25])[O:6][C@@H:7]([CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)[C:8](O[Si](C(C)(C)C)(C)C)=[O:9])([CH3:4])[CH3:3].C(Cl)(=O)C([Cl:30])=O>CN(C)C=O.C(Cl)Cl>[CH3:1][C:2]([Si:5]([CH3:26])([CH3:25])[O:6][C@@H:7]([CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)[C:8]([Cl:30])=[O:9])([CH3:4])[CH3:3]To a solution of 21.0 g (53 mmol) of (1,1-dimethylethyl)-dimethylsilyl (2S)-2-((1,1-dimethylethyl)dimethylsilyloxy)-3-phenylpropanoate (3) and five drops of N,N-dimethylformamide in methylene chloride at 0° C. was added 29.3 mL (59 mmol) of a 2.0M solution of oxalyl chloride in methylene chloride over a 30 min period. The cooling bath was removed and the reaction mixture was allowed to stir at room temperature for 18 hours. The solvent and excess oxalyl chloride were removed by rotary evaporation resulting in a yellow liquid. Purification by vacuum distillation afforded 12.7 g (80%) of (2S)-2-((1,1-dimethylethyl)-dimethylsilyloxy)-3-phenylpropanoyl chloride (4) as a clear liquid: bp 88°-90° C. (0.2 mm Hg); 1H NMR (CDCl3) δ-0.215 (s, 3 H), -0.0339 (s, 3 H), 0.840 (s, 9 H), 2.94-3.01 (m, 1 H), 3.23-3.29 (m, 1 H), 4.52-4.56 (m, 1 H), 7.25-7.35 (m, 5 H); 13C NMR (CDCl3) δ175.7, 135.9, 129.8, 128.4, 127.1, 81.1, 40.8, 25.5, 18.0, -5.40, -5.76.
Wird geladen…
