Metal‐free deoxygenation of α‐hydroxy carbonyl compounds and beyond

Efficient deoxygenation methods are needed now more than ever in the chemist's toolbox to convert biomass‐derived molecules such as carbohydrates into useful chemicals. Late‐stage deoxygenation of drug candidates constitutes also an interesting option to fine tune their drug‐like properties. Metal‐based processes, as exemplified by the Barton–McCombie reaction, have long dominated the field. The development of metal‐free alcohol deoxygenation reactions represents however a challenge that has to be tackled to circumvent drawbacks associated with metal‐based reagents including cost and toxicity. Deoxygenation of alcohols may be assisted by the presence in α‐position of an electron‐withdrawing group. This review provides an overview of metal‐free methods that have been developed in the past decades for the direct, one‐step deoxygenation of α‐hydroxyl carbonyl compounds