Valorization of Ambient Pressure CO2 via Sustainable Catalytic Strategies

As one of the most abundant greenhouse gases, carbon dioxide (CO₂) poses a major environmental challenge but also offers a unique opportunity. Its direct conversion into valuable products offers a sustainable route to emission reduction and a circular carbon economy. CO2 valorization can proceed through both non-reductive and reductive pathways. In both cases, truly sustainable processes require careful control of reaction conditions, since the need for high CO₂ pressures impacts energy consumption and overall costs. In this work, we present two catalytic systems for the non-reductive valorization of CO2 at ambient pressure. First, the biocompatible cinchonine hydrochloride was found to be able to catalyze the cycloaddition of CO2 to aziridines, enabling the 100% atom-economical synthesis of oxazolidin-2-ones, key pharmaceutical intermediates and organic synthons. The excellent regioselectivity and catalyst stability enhanced the high synthetic value of this approach. On the other side, we developed a mild, two step protocol for the synthesis of organic ureas using ambient pressure CO2. Initially, the reaction of this gas with amines and CH3I in the presence of DBU (1,8-diazabiciclo(5.4.0)undec-7-ene) allowed the formation of methyl carbamates. Subsequently, these carbamates reacted with a second amine molecule in the presence of AlCl₃ to yield the desired ureas. Optimization of both steps led to a process characterized by direct CO₂ fixation, low energy input and amine recoverability, offering a green and practical route to valuable ureas from waste CO₂. Together, these methodologies demonstrate the potential of ambient pressure CO₂ valorization as a viable and sustainable strategy for the synthesis of fine chemicals.