Cyclic sulfones are obtained in up to 92% yield by double conjugate addition of Rongalite (sodium hydroxymethyl sulfinate) to dienones. The major product in each case is the kinetic trans-isomer of the 3,5-disubstituted ketosulfone. Eleven examples, including aryl and alkyl substituted substrates, are reported. The advantages of the method are its experimental simplicity, tolerance for both protic and oxidation-sensitive functional groups, and sterically challenging substrates. The work also significantly expands the scope of Rongalite as a conjugate nucleophile.
- Conjugate addition