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Probing Catalyst Speciation in Pd-MPAAM-Catalyzed Enantioselective C(sp³)–H Arylation: Catalyst Improvement via Destabilization of Off-Cycle Species

Hao, Wei and Bay, Katherine L. and Harris, Caleb F. and King, Daniel S. and Guzei, Ilia A. and Aristov, Michael M. and Zhuang, Zhe and Plata, R. Erik and Hill, David E. and Houk, K. N. and Berry, John F. and Yu, Jin-Quan and Blackmond, Donna G. (2021) Probing Catalyst Speciation in Pd-MPAAM-Catalyzed Enantioselective C(sp³)–H Arylation: Catalyst Improvement via Destabilization of Off-Cycle Species. ACS Catalysis, 11 (17). pp. 11040-11048. ISSN 2155-5435. doi:10.1021/acscatal.1c02805. https://resolver.caltech.edu/CaltechAUTHORS:20211008-224638096

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Abstract

Chiral monoprotected aminoethyl amine (MPAAM) ligands were recently reported to facilitate enantioselective Pd-catalyzed arylation of strong cyclopropane C(sp³)–H bonds. Herein, we describe detailed experimental and theoretical investigations into the influence of MPAAM ligands, L1 and L2, as well as a monoprotected aminoethyl thioether (MPAThio) ligand, L3, on the reaction kinetics, product enantioselectivity, and turnover number. We show an unusual negative nonlinear effect in ligand enantiopurity on rate and ee that has not been shown previously in CH activation reactions, along with a negative dependence of the ligand concentration on the reaction rate. NMR titrations, kinetic modeling, crystal structures, and DFT calculations implicate the concentration-dependent formation of stable, off-cycle, homoleptic Pd(L)₂ species in the presence of L1 or L3. However, in the L2 system, the results suggest that only the catalytically active, monosubstituted [Pd(L)(OAc)] species is formed, regardless of ligand concentration, demonstrating the subtle influence of the ligand structure on the reaction kinetics and mechanism. The effect of these mechanistic findings on ligand design is demonstrated by the results for a new ligand in the MPAAM family, L2, which exhibits higher reaction rates.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acscatal.1c02805DOIArticle
ORCID:
AuthorORCID
Hao, Wei0000-0001-9493-6894
Bay, Katherine L.0000-0002-9917-8188
Harris, Caleb F.0000-0002-6844-8923
Guzei, Ilia A.0000-0003-1976-7386
Zhuang, Zhe0000-0001-6679-0496
Hill, David E.0000-0002-7326-2509
Houk, K. N.0000-0002-8387-5261
Berry, John F.0000-0002-6805-0640
Yu, Jin-Quan0000-0003-3560-5774
Blackmond, Donna G.0000-0001-9829-8375
Alternate Title:Probing Catalyst Speciation in Pd-MPAAM-Catalyzed Enantioselective C(sp3)–H Arylation: Catalyst Improvement via Destabilization of Off-Cycle Species
Additional Information:© 2021 American Chemical Society. Received 22 June 2021. Revised 5 August 2021. Published online 20 August 2021. Published in issue 3 September 2021. This work was supported by the National Science Foundation (USA) under the NSF Center for Selective C–H Functionalization (CHE-1700982). Computations were performed on the Hoffman2 cluster at UCLA and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the NSF (OCI-1053575). Dr. Jason Chen and Brittany Sanchez of the Scripps Automated Synthesis Center are acknowledged for valuable discussions and guidance on analytical methods. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
NSFCHE-1700982
NSFOCI-1053575
NSF Graduate Research FellowshipDGE-1747503
Subject Keywords:C−H activation; kinetics; nonlinear effects; enantioselective catalysis; Pd catalysis; reaction mechanism
Issue or Number:17
DOI:10.1021/acscatal.1c02805
Record Number:CaltechAUTHORS:20211008-224638096
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20211008-224638096
Official Citation:Probing Catalyst Speciation in Pd-MPAAM-Catalyzed Enantioselective C(sp3)–H Arylation: Catalyst Improvement via Destabilization of Off-Cycle Species Wei Hao, Katherine L. Bay, Caleb F. Harris, Daniel S. King, Ilia A. Guzei, Michael M. Aristov, Zhe Zhuang, R. Erik Plata, David E. Hill, K. N. Houk, John F. Berry, Jin-Quan Yu, and Donna G. Blackmond ACS Catalysis 2021 11 (17), 11040-11048 DOI: 10.1021/acscatal.1c02805
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111340
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:11 Oct 2021 14:50
Last Modified:11 Oct 2021 14:50

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