CO[CH:3]([O:10][CH3:11])[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.[C:12]1(C)C=CC(S([O-])(=O)=O)=C[CH:13]=1.[NH+]1C=CC=C[CH:24]=1.[OH-:29].[Na+]>C1(C)C=CC=CC=1>[CH3:12][C@@H:13]1[C@@H:11]([CH3:24])[O:10][CH:3]([C:4]2[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=2)[O:29]1A solution of 300 g (3.33 mol) of 2R,3R-butanediol, 422 g (2.78 mol) of benzaldehyde dimethyl acetal and 7.0 g (27.7 mmol) of pyridinium p-toluenesulphonate in 1.2 l of toluene was heated to 50° C. At 600-800 mbar, ca. 400 ml of distillate were taken off over the course of 3 hours. It was cooled and the reaction mixture was added to 500 ml of a 1 M sodium hydroxide solution. The phases were separated and the organic phase was washed twice with in each case 500 ml of water. The organic phase was dried azeotropically, with ca. 250 ml of toluene being distilled off.
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