Selective Electrosynthetic Hydrocarboxylation of α,β‐Unsaturated Esters with Carbon Dioxide**

Abstract

The carboxylation of low‐value commodity chemicals to provide higher‐value carboxylic acids is of significant interest. Recently alternative routes to the traditional hydroformylation processes that used potentially toxic carbon monoxide and a transition metal catalyst have appeared. A significant challenge has been the selectivity observed for olefin carboxylation. Photochemical methods have shown a viable route towards the hydrocarboxylation of α,β‐unsaturated alkenes but rely on the use of an excess reducing or amine reagent. Herein we report our investigations of an electrochemical approach that is able to hydrocarboxylate α,β‐unsaturated alkenes with excellent regioselectivity and the ability to carboxylate hindered substrates to afford α‐quaternary center carboxylic acids. The reported process requires no chromatography and the products are purified by simple crystallization from the reaction mixture after work‐up.

Catalyst- and Additive-Free Electrochemical CO2 Fixation into Morita–Baylis–Hillman Acetates

“…From the data collected in Scheme 2 and following literature precedents on the electrochemical reductive carboxylation of electron-deficient olefins, 7i j the reaction mechanism depicted in Scheme 3a is tentatively proposed. Cathodic reduction of 1 ( 1a : –2.08 V vs SCE, see the Supporting Information) renders intermediate radical anion B that, upon successive reduction and loss of the acetate anion, gives key intermediate A (path A).…”

A comparative overview of the electrochemical valorization and incorporation of CO2 in industrially relevant compounds

“…In the carboxylations involving double CQC or CQN bonds (Table 1, entries 1-10), [115][116][117][118][119][120][121][122][123][124] a non-sacrificial Pt 115 or C 116 anode can be used when triethanolamine (TEOA) is added as a sacrificial reactant (entries 1 and 2, respectively); alternatively, a solvent like THF is used, which itself undergoes anodic oxidation (entry 3). 117 However, these methods only shift the problem of identifying an anodic counterreaction and still produce unwanted byproducts.…”

Ketone–Olefin Coupling of Aliphatic and Aromatic Carbonyls Catalyzed by Excited-State Acridine Radicals

“…Generation of olefin anion radicals through SET pathways have also been proven to be effective methods for ketone–olefin coupling. For example, electrochemically generated olefin anion radicals can undergo ketone–olefin coupling and hydroxycarboxylation reactions by leveraging the strong nucleophilicity of these radical species . Challenges remain with electrochemical methods in over-reduction of the olefin.…”