Base-Mediated Direct Carboxylation of Heteroarenes with CO2

Abstract

The characteristic base medium system synergized from Cs2CO3 and t-BuOK is conducted to the direct carboxylation of imidazoles with CO2 in good yield. And oxygen or thia heterocyclic arenes are of the same carboxylation reactivity with CO2 in the catalysis. Density functional theory shows that in situ construction of t-BuOCs is an endothermic process of 38.31 kJ/mol. t-BuOCs can promote the deprotonation of substrates by forming active C-Cs bond in a rather low energy of HOMO (t-BuOCs)−LUMO (imidazole) of 0.28 eV gap, which favor the electrophilic insertion of CO2 by releasing 94.13 kJ/mol of heat.

Visible-light-driven photocatalytic carboxylation to aromatic carboxylic acids with CO2

“…However, these traditional methods suffer from disadvantages such as environmental pollution, harsh reaction conditions, or high energy-consumption. Examples include CO oxidative carbonylation [8][9][10] and carboxylation of aryl compounds with CO 2 , 11,12 formic acid and its derivatives, [13][14][15][16] tetrachloromethane, [17][18][19] carbonyls of transition metals, 20,21 di-tert-butyl dicarbonate, 22 alkyl metal carbonates, 23 silacarboxylic acid, 24 etc. CO 2 is an abundant, nontoxic, nonflammable, and renewable gas that influences the global warming.…”