We report a Michael-type cyanation reaction of coumarins by using CO2 as a catalyst. The delivery of the nucleophilic cyanide was realized by catalytic amounts of CO2, which forms cyanoformate and bicarbonate in the presence of water. Under ambient conditions, CO2-catalyzed reactions afforded high chemo- and diastereoselectivity of β-nitrile carbonyls, whereas only low reactivities were observed under argon or N2. Computational and experimental data suggest the catalytic role of CO2, which functions as a Lewis acid, and a protecting group to mask the reactivity of the product, suppressing byproducts and polymerization. The utility of this convenient method was demonstrated by preparing biologically relevant heterocyclic compounds with ease.

Rhodonoid natural products are found in nature as a scalemic mixture. This interesting phytochemical feature is presumed to originate from a reversible electrocyclic ring opening of the chromene core present in the biogenetic precursors of rhodonoids. Herein, we systematically investigated factors that are responsible for this racemization event. This eventually led us to complete the asymmetric total synthesis of rhodonoids A, C, D, and G.

The first total synthesis of (+)-dimericbiscognienyne A is described. Key to the successful access to (+)-dimericbiscognienyne A was a biosynthetically inspired Diels−Alder reaction between two differential epoxyquinoid monomers and the subsequent intramolecular hemiacetal formation. The selective formation of the natural product among other possible diastereomers during the late-stage [4+2] cycloaddition reaction was investigated by DFT calculations and experimental control studies.

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 CO2-functionalization often suffer from low efficiency with highly reactive substrates. We recently reported mild carboxylation of aldehydes to furnish α-keto acids – a building block for chiral α-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 CO2-functionalization step, implying a potential role of CO2 in prebiotic evolution of organic molecules in the primordial soup.1 Introduction: Aldehydes, Benzoins, Carboxylic Acids2 CO2-Activation: NHC, Cyanide, Lewis Acid and Water3 A Breslow Intermediate: Benzoin Reaction vs. Carboxylation with CO2 4 Carboxylation in the Primordial Soup5 Conclusion