Seleno-Michael Reaction of Stable Functionalised Alkyl Selenols: A Versatile Tool for the Synthesis of Acyclic and Cyclic Unsymmetrical Alkyl and Vinyl Selenides

Seleno-Michael additions of stable functionalised primary alkyl selenols to activated alkenes and alkynes are described. In the presence of Al2O3, -hydroxy-, -amino-, and -mercapto selenols react smoothly with electron-poor alkenes and alkynes to afford the corresponding unsymmetrical functionalised dialkyl- and alkyl-vinyl-selenides in good yield. The very mild conditions allow a broad range of selenols and Michael acceptors to be converted into the corresponding synthetically valuable seleno-Michael adducts, demonstrating high selectivity and excellent functional group tolerance. Hydroxy- and mercapto-substituted vinyl selenides were efficiently employed for the synthesis of functionalised 1,3-oxaselenolanes, 1,3-thiaselenolanes, and 1,4-thiaselenanes through intramolecular oxa- and thia-Michael additions. Furthermore, a NaH-promoted lactonization enables the synthesis of variously substituted 2-oxo-1,4-oxaselenanes from hydroxy-vinyl-selenides. Evaluation of thiol peroxidase-like properties of novel functionalised organoselenides demonstrated that they possess a remarkable catalytic antioxidant activity