(3S,4R)-4-amino-3-hydroxy-2,2-dimethyl-chroman-6-carbonitrile → (3R,4S)-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile

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Reaction Steps

A mixture of trans-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (32.74 g) and (+)-di-p-toluoyl-D-tartaric acid (57.95 g) was dissolved in ethanol (85 ml) under reflux. The mixture was cooled to room temperature and stood for 4 days to give a white precipitate. This precipitate was collected by filtration, washed with a mixture of ethanol and diisopropyl ether (100 ml, 1:2), and recrystallized from ethanol (80 ml) to give (+)-di-p-toluoyl-D-tartaric acid salt of (3R,4S)-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (19.20 g).

Provenance & Evidence