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.

Direct and Selective Electrocarboxylation of Styrene Oxides with CO2 for Accessing β‐Hydroxy Acids

“…As shown in Figure 2C, the introduction of saturated CO 2 into the 1 aj solution would cause a positive shift at the reduction potential of tetrahydrofuran (Figure 2C, c and d). Recently, electrochemically generated CO 2 ⋅ − has been proposed as a key initiator to conduct electron transfer with olefin substrates during electrochemical carboxylation [19a,d, 28] . An isotope labeling experiment using 13 CO 2 was conducted under standard conditions, and oxalic acid and formic acid products were detected by 13 C NMR (Scheme 3, b), confirming the formation of CO 2 ⋅ − during the present electrocarboxylation reaction.…”

Short electrochemical asymmetric synthesis of (+)-N-acetylcolchinol

“…The reinvigorated interest in electrochemical methodology for organic synthesis, [22][23][24][25][26] and our own recent experience in this field, [27][28][29] prompted us to design a retrosynthetic sequence for N-acetylcolchinol 3, where two out of four steps are carried out electrochemically (Scheme 2). The first disconnection relies on the C-H/C-H coupling of electron-reach aromatic compound 7.…”

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

“…This second possibility includes reductive activation of C-LG bonds (LG – is a leaving group, often a halide ion) ( Meng et al, 2017 ; Isse et al, 1998 ; Isse et al, 2002 ; Isse and Gennaro, 2002 ; Scialdone et al, 2008 ; Durante et al, 2013 ) of C=C or C=N double bonds ( Seo et al, 2017 ; Fan et al, 2018 ; Chen et al, 2020 ; Fan et al, 2018 ; Schmalzbauer et al, 2020 ) and of C-H bonds ( Gui et al, 2017 ; Seo et al, 2017 ; He et al, 2020 ). Recent examples include activation of substituted olefins ( Alkayal et al, 2020 ), of diverse carbonyl compounds ( Okumura and Uozumi, 2021 ) including α-ketoamides and α-ketoesters ( Cao et al, 2021 ), α,β-unsaturated esters ( Sheta et al, 2021 ) and ketones ( Chen et al, 2020 ), and of aldimines generated in situ for α-aminoacid synthesis ( Naito et al, 2021 ).…”