CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions

Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide...

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Bibliographic Details
Published in:Chemistry : a European journal 2021-01, Vol.27 (1), p.228-232
Main Authors: Juhl, Martin, Petersen, Allan R., Lee, Ji‐Woong
Format: Article
Language:English
Subjects:
Carbon dioxide
Catalysts
Chemical reactions
Chemistry
cyanohydrins
elongation
homologation
Homology
Inert atmospheres
Polyols
Potassium cyanide
Protecting groups
Reagents
xanthate
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Summary:Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one 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, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2‐mediated selective cyanohydrin synthesis 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‐ and arylaldehydes, KCN and an atmospheric pressure of CO2. Carbon dioxide promotes cyanohydrins synthesis, enabling facile and iterative homologation reactions for organic synthesis. This traceless, practical and atom‐efficient cyanohydrin synthesis shows a broad substrate scope with high isolated yields of synthetically versatile cyanohydrins. The use of CO2 can be productive in chemical reactions undergoing anionic intermediates and negatively charged transitions states, which can be stabilized by Lewis‐acidic CO2.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.202003623