Olefins from alcohols via catalytic acceptorless dehydrogenation coupling reactions

Abstract

Olefins serve as essential building blocks for creating a wide range of molecular structures, including pharmaceuticals, polymers, and various natural products. In recent years, homogeneous transition-metal catalysis has emerged as a highly efficient method for synthesizing carbon–carbon double bonds in a cascade manner. Among the various approaches to introducing unsaturation, the catalytic acceptorless dehydrogenation coupling (ADC) reactions stand out due to their atom economy and eco-benign characteristics. By dehydrogenating alcohol, ADC produces aldehydes or ketones, which then undergo a condensation reaction with another molecule to yield an unsaturated product. The only byproducts of this process are H₂ and H₂O, which make the ADC reaction superior to the traditional way of producing chemicals. Surprisingly, despite the significance of olefins, there is currently no dedicated review article that specifically addresses catalytic routes to olefins from alcohols (A2O) via the ADC method. This review article aims to highlight the latest advancements in olefination reactions involving various substrates, including carbonyl compounds, phosphorus ylides and substrates with acidic α-hydrogens (such as sulfones, alkyl-substituted N-heteroarenes, and nitriles). Various aspects of metal–ligand cooperation (MLC) and their application are also discussed in brief detail. MLC involving bi-functional catalysts, where the metal center and the ligand jointly participate in the reaction, has shown great potential in ADC reactions. By exploring these catalytic pathways, we hope to inspire researchers to develop novel methods for olefin synthesis using abundant feedstocks.