N-ETHYLDIISOPROPYLAMINE AND SULFUR-DIOXIDE SOLUTIONS .2. REACTIONS WITH CONJUGATE ACCEPTERS

Solutions of sulfur dioxide and N-ethyldiisopropylamine (EDIA) are abl e to reduce alpha,beta-unsaturated-gamma-dicarbonyl compounds (esters or ketones) into alpha-dicarbonyl alkanes. In contrast, monoactivated Michael accepters, such as acrylates, give symmetrical sulfones. These processes involve the conjugate addition of HSO2-, formed from a char ge-transfer complex between EDIA and SO2. Secondary amines are formed as byproducts. Triethylamine, which forms a more stable complex with s ulfur dioxide than EDIA, is far less reactive toward the same substrat es.