[OH:1][C@@H:2]([C:6]([O:19][CH3:20])([C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[C:3]([OH:5])=[O:4].C[O-].[Na+].[CH3:24]N(C=O)C.COS(OC)(=O)=O>O>[OH:1][C@@H:2]([C:6]([O:19][CH3:20])([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)[C:3]([O:5][CH3:24])=[O:4]54.4 g (200 mmol) of (S)-2-hydroxy-3-methoxy-3,3-diphenylpropionic acid were introduced with 10.8 g (200 mmol) of sodium methoxide into 300 ml of DMF. 21 ml (210 mmol) of dimethylsulfate were added dropwise to this suspension over 15 minutes, during which the temperature rises to 50° C. and the suspension becomes mobile. The mixture was stirred overnight and then added to 1.5 l of water and ice. The aqueous phase was extracted twice with 500 ml of ether, and the ether phase was in turn washed with 200 ml of water twice. The organic phase was dried over magnesium sulfate, the desiccant was filtered off, and the solvent was distilled off. 55.8 g of an oil were isolated and were immediately processed further.
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