Issue 22, 2019

The control effects of different scaffolds in chiral phosphoric acids: a case study of enantioselective asymmetric arylation

Abstract

Chiral phosphoric acid (CPA) catalysts with BINOL or SPINOL backbones have attracted immense attention in recent years. Despite a number of successful studies, the theoretical elucidation on the role of the CPA scaffold has rarely been considered, and its effects on enantioselectivity are still far from being understood. Structure inspection shows that axially chiral scaffolds induce a stereogenic central phosphate, and the phosphoric acid functional groups in the (R/S)-BINOL skeleton are identical to those in the (S/R)-SPINOL skeleton. Therefore, a hypothesis is proposed that the orientation of each phosphoric acid functional group regulated by different (R/S) BINOL- and SPINOL-derived scaffolds may control the signs of enantioselectivity (positive or negative ee value) by changing the combination modes of the substrates. In other words, the sign of enantioselectivity (positive or negative ee value) can be tuned with an (R or S) BINOL-derived backbone or an (S or R) SPINOL-derived backbone, respectively. Thus, we elaborate an in-depth mechanistic case study of newly reported CPA-catalyzed enantioselective asymmetric arylation reactions (a–c) catalyzed by CPAs with two different backbones. We found that although the origin of the high enantioselectivity of these three case reactions a–c can be ascribed to favorable C–H⋯O interactions, catalyst and substrate distortion interactions, and electrostatic interactions in the preferential TSs leading to the major products, the signs of enantioselectivity still follow our hypothesis. Our general applicability finding encourages the further development of more effective CPA catalysts and can be used to guide the strategic choice of CPA skeletons.

Graphical abstract: The control effects of different scaffolds in chiral phosphoric acids: a case study of enantioselective asymmetric arylation

Supplementary files

Article information

Article type
Paper
Submitted
17 Upu 2019
Accepted
10 Mph 2019
First published
11 Mph 2019

Catal. Sci. Technol., 2019,9, 6482-6491

The control effects of different scaffolds in chiral phosphoric acids: a case study of enantioselective asymmetric arylation

L. Zhu, H. Mohamed, H. Yuan and J. Zhang, Catal. Sci. Technol., 2019, 9, 6482 DOI: 10.1039/C9CY01420A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements