(-)-Mandelic acid → tert-butyl 4-((1R)-1-aminoethyl)piperidine-1-carboxylate

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Reaction Steps

From the mother liquor of the above mentioned first crystallization tert-butyl 4-(1-aminoethyl)piperidine-1-carboxylate (20 g, 88 mmol) could be isolated (enriched in the other enantiomer). To the material was added (R)-(−)-mandelic acid (14 g, 92 mmol) and acetone (300 mL). The mixture was heated until a clear solution was obtained and allowed to cool to room temperature while stirring. The obtained precipitate was collected, rinsed with some acetone and recrystallized once as described above. After acid base separation, (R)-tert-butyl 4-(1-aminoethyl)piperidine-1-carboxylate was obtained (7.5 g, 99+% ee, 19% yield).

Provenance & Evidence