Does the Configuration at the Metal Matter in Noyori–Ikariya Type Asymmetric Transfer Hydrogenation Catalysts? ACS Catalysis

Andrew M. R. Hall, Daniel B. G. Berry, Jaime N. Crossley, Anna Codina, Ian Clegg, John P. Lowe, Antoine Buchard, Ulrich Hintermair

Research output: Contribution to journalArticlepeer-review

29 Citations (SciVal)

Abstract

Noyori–Ikariya type [(arene)RuCl(TsDPEN)] (TsDPEN, sulfonated diphenyl ethylenediamine) complexes are widely used C═O and C═N reduction catalysts that produce chiral alcohols and amines via a key ruthenium–hydride intermediate that determines the stereochemistry of the product. Whereas many details about the interactions of the pro-chiral substrate with the hydride complex and the nature of the hydrogen transfer from the latter to the former have been investigated over the past 25 years, the role of the stereochemical configuration at the stereogenic ruthenium center in the catalysis has not been elucidated so far. Using operando FlowNMR spectroscopy and nuclear Overhauser effect spectroscopy, we show the existence of two diastereomeric hydride complexes under reaction conditions, assign their absolute configurations in solution, and monitor their interconversion during transfer hydrogenation catalysis. Configurational analysis and multifunctional density functional theory (DFT) calculations show the λ-(R,R)SRu configured [(mesitylene)RuH(TsDPEN)] complex to be both thermodynamically and kinetically favored over its λ-(R,R)RRu isomer with the opposite configuration at the metal. Computational analysis of both diastereomeric catalytic manifolds show the major λ-(R,R)SRu configured [(mesitylene)RuH(TsDPEN)] complex to dominate asymmetric ketone reduction catalysis with the minor λ-(R,R)RRu [(mesitylene)RuH(TsDPEN)] stereoisomer being both less active and less enantioselective. These findings also hold true for a tethered catalyst derivative with a propyl linker between the arene and TsDPEN ligands and thus show enantioselective transfer hydrogenation catalysis with Noyori–Ikariya complexes to proceed via a lock-and-key mechanism.
Original languageEnglish
Pages (from-to)13649-13659
Number of pages11
JournalACS Catalysis
Volume11
Issue number21
DOIs
Publication statusPublished - 26 Oct 2021

Bibliographical note

doi: 10.1021/acscatal.1c03636

Funding

This work was supported by a Research Grant from the Royal Society (Y0603), the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1), the Dynamic Reaction Monitoring Facility at the University of Bath (EP/P001475/1), and Bruker UK Ltd. U.H. and A.B. acknowledge the Centre for Sustainable Chemical Technologies for Whorrod Research Fellowships and the Royal Society for University Research Fellowships (U.H.: UF160458; A.B.: UF160021). The authors would like to thank Dr. Catherine Lyall from the University of Bath as well as Dr. Antonio Zanotti-Gerosa from Johnson Matthey for their support and assistance with this project.

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