Rongalite as a sulfone source: a novel copper-catalyzed sulfur dioxide anion incorporation process.

A novel copper-catalyzed sulfur dioxide anion incorporation cascade for the synthesis of 1-thiaflavanone sulfones has been disclosed using rongalite as an economic and safe sulfone source. A series of 1-thiaflavanone sulfones were synthesized from easily prepared 2'-iodochalcone derivatives in excellent yields. This transformation proceeds through consecutive formation of two C-S bonds, which is the first example of SO- being used to construct sulfone motifs under copper-catalyzed conditions.