FORMATION AND REACTIVITY OF THE ADDITION PRODUCTS OF ALKOXIDES AND THIOLATE ANIONS TO VINYL SELENONES

Article abstract of DOI:10.1016/S0040-4020(01)82072-X

Vinyl selenones react with sodium methanethiolate in methanol to give the product of conjugate addition and subsequent displacement of the selenonyl group.On the contrary, the same reaction carried out with alkoxide anions affords the conjugate addition products in excellent yields.These β-alkoxy alkyl phenyl selenones are stable compounds which can react in several ways with loss of the selenonyl group.Their reactions with MeONa or MeSNa have been investigated both in MeOH and in DMF.The products observed derive from substitution and elimination processes as well as from retro Michael reactions followed by nucleophilic substitution of the vinyl selenone thus generated.These results indicate that the ArSeO2 is a strong electron attracting group with peculiar properties.Beside making acidic the α-hydrogen atoms it activates the carbon-carbon double bond towards the addition of anionic reagents and it acts as a good leaving group in nucleophilic substitution, both aliphatic and vinylic, and in elimination reactions.The appropriate choice of the reagent and of the solvent allows to direct the reaction towards the desired products.Useful synthetic applications of these reactions are presented.