The Sonogashira cross-coupling is one of the most fundamental C–C bond-forming reactions, wherein the strategic value of an alkyne moiety has found widespread applications at the frontiers of organic chemistry, materials science and drug discovery as the cornerstone building block of chemical synthesis. Although traditional variants of Sonogashira cross-coupling involve aryl halides and pseudohalides as electrophiles, recently, tremendous advances have been made in the unconventional disconnection exploiting common carboxylic acids by a decarbonylation/transmetalation pathway. This manifold (1) permits one to take advantage of carboxylic acids as a ubiquitous class of substrates in organic synthesis that are derived from an orthogonal pool of precursors to aryl halides and pseudohalides and (2) combines the benefits of the palladium-catalyzed C(sp 2 )–C(sp) coupling of terminal alkynes with the inherent presence of the carboxylic acid moiety in pharmaceuticals, natural products and organic materials. In this highlight article, we summarize the recent progress in the decarbonylative Sonogashira cross-coupling of carboxylic acid electrophiles to produce arylalkynes and conjugated enynes as a novel avenue for chemical synthesis, whereby a large number of chemical reactions critically rely on transformations of alkynes.
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Palladium-catalyzed cross-couplings by C–O bond activation
Although palladium-catalyzed cross-coupling of aryl halides and reactive pseudohalides has revolutionized the way organic molecules are constructed today across various fields of chemistry, comparatively less progress has been made in the palladium-catalyzed cross-coupling of less reactive C–O electrophiles. This is despite the fact that the use of phenols and phenol derivatives as bench-stable cross-coupling partners has been well-recognized to bring about major advantages over aryl halides, such as natural abundance of phenols, (2) avoidance of toxic halides, (3) orthogonal cross-coupling conditions, (4) prefunctionalization of phenolic substrates by electrophilic substitution or C–H functionalization, (5) ready availability of phenols from a different pool of precursors than aryl halides. In this review, we present an overview of recent advances made in the field of palladium-catalyzed cross-coupling of C–O electrophiles with a focus on catalytic systems, (2) reaction type, and (3) class of C–O coupling partners. Although the field has been historically dominated by nickel catalysis, it is now evident that the use of more versatile, more functional group tolerant and highly active palladium catalysts supported by appropriately designed ancillary ligands enables the cross-coupling with improved substrate scope and generality, and likely represents a practical solution to the broadly applicable cross-coupling of various C–O bonds across diverse chemical disciplines. The review covers the period through June 2020.
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- Award ID(s):
- 1650766
- NSF-PAR ID:
- 10224904
- Date Published:
- Journal Name:
- Catalysis Science & Technology
- Volume:
- 10
- Issue:
- 17
- ISSN:
- 2044-4753
- Page Range / eLocation ID:
- 5702 to 5739
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0cy01159b
