Bifunctional Copper-Based Photocatalyst for Reductive Pinacol-Type Couplings

A bifunctional copper-based photocatalyst has been prepared that employs a pyrazole-pyridine ligand incorporating a sulfonamide moiety that functions as an intramolecular hydrogen-bond donor for a photochemical PCET process. In typical reductive PCET processes, the photocatalyst and H-bond donor mus...

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Bibliographic Details
Published inACS catalysis Vol. 9; no. 10; pp. 9458 - 9464
Main Authors Caron, Antoine, Morin, Émilie, Collins, Shawn K
Format Journal Article
LanguageEnglish
Published American Chemical Society 04.10.2019
Subjects
copper
photocatalysis
reductive coupling
PCET
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Summary:A bifunctional copper-based photocatalyst has been prepared that employs a pyrazole-pyridine ligand incorporating a sulfonamide moiety that functions as an intramolecular hydrogen-bond donor for a photochemical PCET process. In typical reductive PCET processes, the photocatalyst and H-bond donor must have an appropriate redox potential and pK a, respectively, to promote the PCET. When working in concert in a bifunctional catalyst such as Cu­(pypzs)­(BINAP)­BF4, the pK a of the H-bond donor can have an acidity that is orders of magnitude less and still efficiently promote the PCET process. A reductive pinacol-type coupling can be performed using a base-metal derived photocatalyst to afford valuable diols (24 examples, 46–99% yield), from readily available aldehydes and ketones.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.9b01718