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Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation.

ABSTRACT: The enantioselective amination of C(sp³)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh₂(esp)₂, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C-H amination of substrates bearing pendant hydroxyl groups. Additionally, the quinoline of the chiral cation appears to engage in axial ligation to the rhodium complex, providing improved yields of product versus Rh₂(esp)₂ and highlighting the dual role that the cation is playing. These results underline the potential of using chiral cations to control enantioselectivity in challenging transition-metal-catalyzed transformations.

SUBMITTER: Fanourakis A

PROVIDER: S-EPMC8283762 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation.

Fanourakis Alexander A Williams Benjamin D BD Paterson Kieran J KJ Phipps Robert J RJ

Journal of the American Chemical Society 20210628 27

The enantioselective amination of C(sp3)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh2(esp)2, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C ...[more]

PMID: 34181401

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