Search for: All records

Abstract This Graphical Review provides an overview of amide bond activation achieved by selective oxidative addition of the N–C(O) acyl bond to transition metals and nucleophilic acyl addition, resulting in acyl and decarbonylative coupling, together with key mechanistic details pertaining to amide bond distortion underlying this reactivity manifold. 

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. 

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. 

We report a general and practical palladium-catalyzed intramolecular decarbonylative coupling of thioesters via C–S bond cleavage, decarbonylation and C–S bond reformation. This robust approach shows excellent functional group tolerance and broad substrate scope using a commercially available, cheap, and practical Pd(OAc) 2 catalyst and phosphine ligands. This strategy operates under base-free conditions. The catalytic system represents the simplest method for intramolecular decarbonylation of thioesters by palladium catalysis reported to date. This versatile protocol is readily performed on a gram scale and applied in late-stage drug derivatization.