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

Abstract

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 HSO 2 - , formed from a charge-transfer complex between EDIA and SO 2 . 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