Carboxylates as sources of carbon nucleophiles and electrophiles: comparison of decarboxylative and decarbonylative pathways

Abstract

This tutorial review provides a comparison between the concepts of catalytic decarboxylative and decarbonylative couplings for the ipso-substitution of carboxylate groups, and illustrates their potential benefits over alternative C-C bond-forming reactions. Redox-neutral decarboxylative reactions allow generating organometallic species with nucleophilic reactivity via the extrusion of carbon dioxide from metal carboxylates. Such C-C bond activating processes provide a way of employing carboxylate salts as substitutes for the traditional sources of carbon nucleophiles, i.e. stoichiometric organometallic reagents. If the decarboxylation of carboxylic acids is performed under oxidative conditions, organometallic species with electrophilic reactivity are obtained instead. These can alternatively be accessed via the extrusion of carbon monoxide from acyl-metal species generated via the oxidative addition of activated carboxylic acid derivatives (e.g. acid chlorides, anhydrides or esters) to metal complexes. In the latter two reaction types, carboxylic acids thus become substitutes for organohalides. The complementary redox-neutral and oxidative decarboxylative and decarbonylative reaction modes allow the broad use of carboxylic acids as substrates in C-C bond-forming reactions. Their applicability, scope and limitations are discussed using the examples of Heck reactions, cross-couplings and direct arylations.

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

“…24,25,26,27,28,29,30,31 We were inspired by a report from Myers et al 32,33,34 detailing a palladium catalyzed decarboxylative Heck coupling under mild conditions. Based on those initial reports, our group reported 35 the mildest and most efficient method for aromatic decarboxylation utilizing catalytic amounts of a palladium complex.…”

Gas-phase studies of metal catalyzed decarboxylative cross-coupling reactions of esters

“…Metal catalyzed decarboxylative coupling reactions have been widely studied over the past decade, as highlighted in several reviews and a book chapter [19][20][21][22][23][24][25][26][27].…”

The utilization of copper flow reactors in organic synthesis

“…6 Automation is also a significant advantage employed within flow chemistry reactions, as it allows for better control over time-sensitive synthetic reactions and easier and more rapid reaction optimization, 7 including in situ reaction monitoring. 13 This review will outline the utilization of copper flow reactors in the performance of these reactions, and the incorporation of other technology within the copper reactor, as well as, reported findings. Reactions that have been reported include: 1,3-dipolar cycloadditions ('click' chemistry 9 ), macrocyclizations 10 (via 'click' chemistry), Sonogashira couplings, 11 Ullmann-type reactions 12 and decarboxylations.…”