Resolution of racemic 2-aminocyclohexanol derivatives and their application as ligands in asymmetric catalysis.
A preparatively easy and efficient protocol for the resolution of racemic 2-aminocyclohexanol derivatives is described, delivering both enantiomers with >99% enantiomeric excess (ee) by sequential use of (R)- and (S)-mandelic acid. A simple aqueous workup procedure permits the isolation of the amino alcohols in analytically pure form and the almost quantitative recovery of mandelic acid. Debenzylation of enantiopure trans-2-(N-benzyl)amino-1-cyclohexanol by hydrogenation and subsequent derivatization give access to a broad variety of diversely substituted derivatives. Furthermore, the corresponding cis isomers are readily available. Applications of these optically active aminocyclohexanols in catalyzed asymmetric phenyl transfer reactions to benzaldehydes and transfer hydrogenations of aryl ketones lead to products with up to 96% ee.
Schiffers
Ingo
I
Institut für Organische Chemie der RWTH Aachen, Landoltweg 1, D-52056 Aachen, Germany.
Rantanen
Toni
T
Schmidt
Frank
F
Bergmans
Werner
W
Zani
Lorenzo
L
Bolm
Carsten
C
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry*; D002384:Catalysis; D003511:Cyclohexanols / Q000138:chemical synthesis / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D008024:Ligands; D008333:Mandelic Acids / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
C516358:2-aminocyclohexanol; D000438:Alcohols; D001547:Benzaldehydes; D003511:Cyclohexanols; D007659:Ketones; D008024:Ligands; D008333:Mandelic Acids; C037938:mandelic acid