(S)-mandelic acid → (S)-mandelic acid

Participants

Reaction Conditions

Reaction Steps

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%.

Provenance & Evidence