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Published February 21, 2024 | Published
Journal Article Open

Electrocatalytic Asymmetric Nozaki–Hiyama–Kishi Decarboxylative Coupling: Scope, Applications, and Mechanism

Abstract

The first general enantioselective alkyl-Nozaki–Hiyama–Kishi (NHK) coupling reactions are disclosed herein by employing a Cr-electrocatalytic decarboxylative approach. Using easily accessible aliphatic carboxylic acids (via redox-active esters) as alkyl nucleophile synthons, in combination with aldehydes and enabling additives, chiral secondary alcohols are produced in a good yield with high enantioselectivity under mild reductive electrolysis. This reaction, which cannot be mimicked using stoichiometric metal or organic reductants, tolerates a broad range of functional groups and is successfully applied to dramatically simplify the synthesis of multiple medicinally relevant structures and natural products. Mechanistic studies revealed that this asymmetric alkyl e-NHK reaction was enabled by using catalytic tetrakis(dimethylamino)ethylene, which acts as a key reductive mediator to mediate the electroreduction of the CrIII/chiral ligand complex.

Copyright and License

© 2024 American Chemical Society.

Acknowledgement

This work was supported by the NSF Center for Synthetic Organic Electrochemistry, CHE-2002158 (the discovery and optimization effort). NIGMS (GM-118176) supported the scope and application study. A.C.H. was supported by an NSF Ascend fellowship (award number: 2138035). The authors are grateful to Dr. Laura Pasternack (Scripps Research) for assistance with nuclear magnetic resonance (NMR) spectroscopy, to Dr. Jason Chen, Brittany Sanchez, and Quynh Nguyen Wong (Scripps Automated Synthesis Facility) for assistance with HRMS and chiral SFC analysis. Elemental analysis data were obtained from the CENTC Elemental Analysis Facility at the University of Rochester, funded by NSF CHE-0650456. Mass spectral data were acquired by field desorption ionization mass spectrometry using an JMS-T2000 AccuTOF GC-Alpha (JEOL, Inc). The purchase of the instrument was enabled by funds from DOW Next Generation Instrumentation (CCEC.DOWINSTR-1-GRANT.DOWINSTR). The authors would like to thank Jay Winkler for assistance with CV experiments and Mona Shahgoli for assistance with HRMS experiments, as well as the Caltech CCE NMR facility and Multiuser Mass Spectrometry Laboratory, which is also supported by the NSF CRIF program (CHE-0541745).

 

Conflict of Interest

The authors declare no competing financial interest.

Data Availability

  • All experimental procedures, analysis, and compound characterization data (PDF)

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Additional details

Created:
March 6, 2024
Modified:
March 6, 2024