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A method for the synthesis of sulfides from carboxylic acids via thioester C–S activation and acyl capture has been developed, wherein thioesters serve as dual electrophilic activators of carboxylic acids and S-nucleophiles through the merger of decarbonylative palladium catalysis and sulfur coupling. This new concept employs readily available carboxylic acids as coupling partners to directly intercept sulfur reagents via redox-neutral thioester-enabled cross-over thioetherification. The scope of this platform is demonstrated in the highly selective decarbonylative thioetherification of a variety of carboxylic acids and thioesters, including late-stage derivatization of pharmaceuticals and natural products. This method operates under mild, external base-free, and operationally practical conditions, providing a powerful new framework to unlock aryl electrophiles from carboxylic acids and increase the reactivity by employing common building blocks in organic synthesis.
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Highly-chemoselective step-down reduction of carboxylic acids to aromatic hydrocarbons via palladium catalysis
Aryl carboxylic acids are among the most abundant substrates in chemical synthesis and represent a perfect example of a traceless directing group that is central to many processes in the preparation of pharmaceuticals, natural products and polymers. Herein, we describe a highly selective method for the direct step-down reduction of carboxylic acids to arenes, proceeding via well-defined Pd(0)/( ii ) catalytic cycle. The method shows a remarkably broad substrate scope, enabling to direct the classical acyl reduction towards selective decarbonylation by a redox-neutral mechanism. The utility of this reaction is highlighted in the direct defunctionalization of pharmaceuticals and natural products, and further emphasized in a range of traceless processes using removable carboxylic acids under mild, redox-neutral conditions orthogonal to protodecarboxylation. Extensive DFT computations were conducted to demonstrate preferred selectivity for the reversible oxidative addition and indicated that a versatile hydrogen atom transfer (HAT) pathway is operable.
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- Award ID(s):
- 1650766
- PAR ID:
- 10146146
- Date Published:
- Journal Name:
- Chemical Science
- Volume:
- 10
- Issue:
- 22
- ISSN:
- 2041-6520
- Page Range / eLocation ID:
- 5736 to 5742
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c9sc00892f
