Link to DOI – 10.1002/ejoc.201900838
Eur JOC, 2019, 37, 6320-6332
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.