N-Ethyldiisopropylamine and Sulfur Dioxide Solutions. 2. Reactions with Conjugate Acceptors

Article abstract of DOI:10.1021/jo00088a051

Solutions of sulfur dioxide and N-ethyldiisopropylamine (EDIA) are able to reduce α,β-unsaturated-γ-dicarbonyl compounds (esters or ketones) into α-dicarbonyl alkanes.In contrast, monoactivated Michael acceptors, such as acrylates, give symmetrical sulfones.These processes involve the conjugate addition of HSO2(-), formed from a charge-transfer complex between EDIA and SO2.Secondary amines are formed as byproducts.Triethylamine, which forms a more stable complex with sulfur dioxide than EDIA, is far less reactive toward the same substrates.