Copper‐Catalyzed Direct Carboxylation of CH Bonds with Carbon Dioxide

Abstract

Cooking with gas: Copper complexes serve as excellent catalysts for the direct carboxylation of aromatic heterocyclic CH bonds with CO2, thereby offering an economical and environmentally benign process for the synthesis of heterocyclic carboxylic esters (see scheme; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene). Some active intermediates of this reaction have been isolated and structurally characterized.

Ruthenium-catalysed alkoxycarbonylation of alkenes with carbon dioxide

“…Not only primary alcohols but also secondary alcohols reacted smoothly in moderate to excellent yields, although a longer reaction time was needed for secondary alcohols. Functionalized alcohols with halide and ether groups were well tolerated too (entries [20][21][22][23] Control experiments. To gain more insight into this rutheniumcatalysed C-C bond formation 32,33 with carbon dioxide, a series of control experiments were performed.…”

“…In contrast to all these protocols, the use of abundant CO 2 is desirable. However, because of its thermodynamic and kinetic stability [18][19][20][21] , the catalytic C-C bond formation between carbon dioxide and olefins constitutes one of the most challenging tasks for organometallic chemistry. So far, the reported carboxylation of alkenes with carbon dioxide proceeds only in the presence of (over)stoichiometric amounts of strong or expensive reductants like Et 2 Zn and silanes [22][23][24] .…”

Copper–NHC complexes in catalysis

“…Independently, Hou developed a methodology leading to a range of heterocyclic esters (Scheme 3.1.2) [95]. Scheme 3.1.2: Carboxylation system reported by Hou [95] In both systems, the C-H bond activation is followed by CO 2 insertion and an excess of a strong base is required (Scheme 3.1.3) [95]. The IPr ligand was the most efficient NHC-basedligand, with a high reactivity for boronic and aryl compounds.…”

Carbon Dioxide as a Carbon Resource – Recent Trends and Perspectives

“…An intriguing example for direct carboxylation of aromatic C-H bonds was presented recently by the group of Nolan who introduced gold hydroxy N-heterocyclic carbene (NHC) complexes as catalysts for the reaction of CO 2 with electron-deficient arenes [128 -130]. Shortly after Nolan's report the group of Hou described similar insertions of CO 2 into such arenes using copper chloride NHC complexes [131]. The postulated reaction mechanism is shown in Scheme 15.…”