Polymerization-like mechanism for fixation of CO2 with epoxides by multifunctional organocatalysts

Abstract

The commonly accepted mechanism of CO₂ fixation of epoxides to cyclic carbonates catalyzed by multifunctional non-halide organocatalysts is challenged by our computational DFT-D3 study, which revealed a new polymerization-like mechanism comprising alternate epoxide and CO₂ activation steps and a nested CO₂ activation pathway. We investigated a recently reported CO₂ coupling with epoxide reaction catalyzed by a bis-phenolic multifunctional catalyst. The predicted cis/trans product ratio is in excellent agreement with experimental results. The general applicability of the new mechanism is supported by another diamine-diacid catalyzed CO₂ fixation reaction.