Umpolung Reactivity of Aldehydes toward Carbon Dioxide

Juhl, Martin; Lee, Jiwoong

doi:10.1002/ange.201806569

Cited by 4 publications

(1 citation statement)

References 61 publications

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“…After demonstrating the viability of different kinds of ketones, we turned our attention to more challenging aryl aldehydes. Although umpolung carboxylations of aryl aldehydes with CO 2 are rare 43 , 68 , 69 , α-hydroxycarboxylic acids synthesis typically suffer from low yields, low selectivity, and limited scope. When aryl aldehydes were applied as substrates to the standard reaction conditions, we observed a complicated mixture of products due to intense side reactions, including pinacol coupling and disproportionation, which might arise from the lower steric hindrance of aldehydes and the strong base.…”

Section: Resultsmentioning

confidence: 99%

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Cao

Liao

et al. 2021

Nat Commun

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Photoredox-mediated umpolung strategy provides an alternative pattern for functionalization of carbonyl compounds. However, general approaches towards carboxylation of carbonyl compounds with CO2 remain scarce. Herein, we report a strategy for visible-light photoredox-catalyzed umpolung carboxylation of diverse carbonyl compounds with CO2 by using Lewis acidic chlorosilanes as activating/protecting groups. This strategy is general and practical to generate valuable α-hydroxycarboxylic acids. It works well for challenging alkyl aryl ketones and aryl aldehydes, as well as for α-ketoamides and α-ketoesters, the latter two of which have never been successfully applied in umpolung carboxylations with CO2 (to the best of our knowledge). This reaction features high selectivity, broad substrate scope, good functional group tolerance, mild reaction conditions and facile derivations of products to bioactive compounds, including oxypheonium, mepenzolate bromide, benactyzine, and tiotropium. Moreover, the formation of carbon radicals and carbanions as well as the key role of chlorosilanes are supported by control experiments.

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Section: Resultsmentioning

confidence: 99%

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Cao

Liao

et al. 2021

Nat Commun

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Recent Advances in Electrocarboxylation with CO₂

Wang

Feng

Wang

et al. 2022

Chemistry An Asian Journal

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Carbon dioxide (CO2) is an abundant, inexpensive, renewable C1 resource and the main component of greenhouse gas, thereby the research for its sustainable and efficient conversion has received notable attention in recent years. Electrochemical organic synthesis, as a green and efficient synthetic method, is convinced to be an ideal approach for CO2 utilization. In this review, recent advances in electrocarboxylation with CO2 were summarized through different reaction types, which would disclose the great potential of electrocarboxylation in green organic synthesis.

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CO₂‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**

Juhl

Petersen

Lee

2020

Chemistry A European J

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Thermodynamic andk inetic control of ac hemical process is the key to access desired products and states. Changes are made when ad esired product is not accessible;o ne may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere,t he reaction is essentially not operative due to the unfavored equilibrium. The utilityo f CO 2-mediated selective cyanohydrins ynthesis was further showcased by broadening Kiliani-Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl-a nd arylaldehydes, KCN and an atmospheric pressureo fC O 2. Achemical reaction is governed by kinetics and thermodynamics, and as imultaneous controlo fb oth parameters is a commonp ractice in designing and optimizing chemical reactions. The manipulation of thermodynamic stability of reactants and products will decide the outcome of ac hemical process, while variousr eactionp athways can lead to undesired products thus reducing overall efficiency of the process. [1] To circumvent unwanted reactionp athways, chemists have developed selectivec atalysis,p rotecting groups ("P" in Scheme1), trappingr eagents and reactivity-altered reactants (A' and B'), which in turn can limit the scopea nd generality of the original reaction. In our ongoing pursuit to implement CO 2 in the core of organic synthesis, we sought out ways in which equilibria can be controlled by the use of CO 2-a mild Lewis acid where anionic intermediates can be stabilized. Carbon dioxide is an intrinsicallys table molecule, [2, 3] however,i tc an readily and reversibly react with various nucleophiles. [2, 4] Recent applicationso fc arbond ioxide in organic synthesis showed fruitful successp articularly in CO 2-incorporation , [5] CO 2 as at emporal protecting group for CÀHa ctivation, [6] CO 2 for asymmetricc atalysis [7] and oxidation reactions. [8] We recently investigated the role of CO 2 in ac yanation reaction, [9] where CO 2 can be used in catalytic amountst of acilitate the stereoselective transformation of activated electrophiles via 1,4-conjugate addition reactions. Cyanohydrin synthesis À1,2-cyanide addition reactions to carbonyls-is one of the oldestC ÀCb ond-forming reactions using HCN as ac yanide source. [10] Despite the high utility of cyanohydrins in organic synthesis [11-14] the use of HCN reduces its application potential due to its volatile nature and health risks. Recent research activitiesi nc yanohydrin synthesis are mainly performed by using TMSCN 15] and cyanoformate [16] as aH CN surrogate. [11, 12, 17] These reagents suffer from poor atom economyw hen unprotected cyanohydrins are desired. Furthermore,t he cyanation reactions with in situ generated HCN (from am ixture of TMSCNa nd an alcohol) are limitedb yt he instability of the cyani...

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Umpolung Reactivity of Aldehydes toward Carbon Dioxide

Cited by 4 publications

References 61 publications

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Recent Advances in Electrocarboxylation with CO₂

CO₂‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**

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Umpolung Reactivity of Aldehydes toward Carbon Dioxide

Cited by 4 publications

References 61 publications

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO2

Recent Advances in Electrocarboxylation with CO2

CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**

Contact Info

Product

Resources

About

Recent Advances in Electrocarboxylation with CO₂

CO₂‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**