Aldehyde Carboxylation: A Concise DFT Mechanistic Study and a Hypothetical Role of CO (2) in the Origin of Life

Abstract

Carbon dioxide is arguably one of the most stable carbon-based molecules, yet enzymatic carbon fixation processes enabled the sustainable life cycle on Earth. Chemical reactions involving CO (2) -functionalization often suffer from low efficiency with highly reactive substrates. We recently reported mild carboxylation of aldehydes to furnish -keto acids - a building block for chiral -amino acids via reductive amination. Here, we discuss potential reaction mechanisms of aldehyde carboxylation reactions based on two promoters: NHCs and KCN in the carboxylation reaction. New DFT mechanistic studies suggested a lower reaction barrier for a CO (2) -functionalization step, implying a potential role of CO (2) in prebiotic evolution of organic molecules in the primordial soup. 1 Introduction: Aldehydes, Benzoins, Carboxylic Acids 2 CO (2) -Activation: NHC, Cyanide, Lewis Acid and Water 3 A Breslow Intermediate: Benzoin Reaction vs. Carboxylation with CO (2) 4 Carboxylation in the Primordial Soup 5 Conclusion