(S)-mandelic acid → (S)-mandelic acid

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[C:1]([OH:11])(=[O:10])[C@H:2]([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)[OH:3].[CH3:12][C@H:13]([N:20]1[CH2:29][CH2:28][CH2:27][CH2:26][CH:21]1[C:22]([O:24][CH3:25])=[O:23])[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1>C1(C)C=CC=CC=1>[C:1]([OH:11])(=[O:10])[C@H:2]([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)[OH:3].[CH3:12][C@H:13]([N:20]1[CH2:29][CH2:28][CH2:27][CH2:26][C@H:21]1[C:22]([O:24][CH3:25])=[O:23])[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1

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온도: 70 °C

실험 절차

L-(+)-mandelic acid (1.52 g) and toluene (8.67 g) were mixed and warmed to 70° C. To the solution was added a mixture of methyl N-[(S)-α-methylbenzyl]-(RS)-pipecolate (2.47 g) and toluene (8.67 g). The mixture was stirred for 0.5 hour, and the L-(+)-mandelic acid salt of methyl N-[(S)-α-methylbenzyl]-(S)-pipecolate, which was obtained in Example 6 (73% d.e.), as a seed crystal was added thereto. After this, the mixture was cooled to 0° C. over 3.5 hours with stirring. The crystals formed were separated by filtration and washed with cold toluene to yield an L-(+)-mandelic acid salt of methyl N-[(S)-α-methylbenzyl]-(S)-pipecolate (2.49 g) in 95.2% d.e. and a yield of 41.3%.