Electrochemical CO2 fixation with amines to synthesize α-amino acids

• Published in: Chem catalysis Vol. 4; no. 11; p. 101158
• Main Authors: Cao, Yimeng, Chen, Jun, Ding, Chunmei, Zhang, Ying, Chi, Haibo, Liu, Yan, Li, Can
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 21.11.2024
• Subjects: catalyst design; dehydrogenation of amines; electrocarboxylation; organic electrochemical synthesis; α-amino acids synthesis; dehydrogenation of amines; electrocarboxylation; organic electrochemical synthesis; SDG13: Climate action; SDG7: Affordable and clean energy; catalyst design; α-amino acids synthesis
• ISSN: 2667-1093; 2667-1093
• DOI: 10.1016/j.checat.2024.101158

α-Amino acids (α-aa) play a significant role in pharmaceutical and chemical industries. Here, we reported an electrochemical tandem system that couples the anodic dehydrogenation of amines and the cathodic carboxylation of imines. Based on a designed Lewis acid (LA)-enriched CeO2 with indium (denoted as In-CeOx) as cathodic electrocatalysts, we achieved 82% and 92% yields of stable imines and α-aa in a membrane-separated cell system, respectively. In a membrane-free system, quaternary or cyclic α-aa could be directly obtained from amines and CO2 with up to 83% yield. Mechanistic investigations have elucidated that the incorporation of indium (In) yields elevated levels of LA sites. These enhanced LA sites play a pivotal role in facilitating the capture and activation of imines. This function of In-CeOx, coupled with CO2 activation mediated by In species, is proven to be crucial for achieving high reactivity and selectivity in the cathodic carboxylation reaction. [Display omitted] •Developed an electrochemical tandem system for α-amino acid synthesis•The system is suitable for the synthesis of quaternary or cyclic α-amino acids•Fine chemicals could be obtained through rational designing of electrochemical systems•Lewis acid-enriched catalyst to improve imine electrocarboxylation performance α-Amino acids (α-aa) are crucial structural motifs found extensively in numerous biologically and pharmaceutically significant compounds. Over the past few decades, the convenient and efficient synthesis of α-aa has been a subject of ongoing interest. In this study, we developed an electrochemical strategy for the synthesis of α-aa, which involves the fixation of CO2 with amines by coupling the anodic dehydrogenation of amines and the cathodic carboxylation of imines. We achieved yields of 82% for imines and 92% for α-aa using a membrane-separated, two-compartment cell system. In a membrane-free system, α-aa could be directly obtained from amines and CO2 with yields of up to 83%. This tandem system offers new insights into the economical and environmentally friendly synthesis of amino acids. This study developed an electrochemical tandem system that couples the anodic dehydrogenation of amines and the cathodic carboxylation of imines to realize the direct synthesis of unprotected α-amino acids with amine and CO2. The method proved that fine chemicals could be achieved in the electrochemical system through rational designing of electrode materials.