Asymmetric Hydrogenation Catalyzed by (Achiral Base)bis(dimethylglyoximato)cobalt(II)-Chiral Cocatalyst System

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Abstract
Chiral tertiary amines with a secondary amide group at α- or β-carbon were prepared, and an asymmetric hydrogenation of methyl 2-(acetylamino)acrylate and N,N′-dimethyl-5-benzylidenehydantoin catalyzed by achiral base-coordinated bis(dimethylglyoximato)cobalt(II)-chiral cocatalyst system was examined by using each of them as the cocatalyst. The enantiomeric excess of N,N′-dimethyl-5-benzylhydantoin reached 79.1% with (S)-N-[(R)-1-phenylethyl]-2-quinuclidinecarboxamide as the cocatalyst. Remarkable differences were observed in the enantioselectivities between the two substrates for the same cocatalysts. Discussion about the conformations of the cocatalysts and substrates led to proposed models of chirality-recognizing transition states.