Directing-Group-Assisted C(sp2)-H Arylsulfonylation from Sulfur Dioxide.

A straightforward and stereoselective preparation of (Z)-β-alkenyl sulfones through a reaction of N-tosyl acrylamides, 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide, and aryldiazonium tetrafluoroborates under copper catalysis is accomplished. The direct C(sp2)-H arylsulfonylation of acrylamides using sulfur dioxide as the sulfonyl source in the presence of copper trifluoroacetate proceeds smoothly, giving rise to (Z)-β-alkenyl sulfones in good yields. During the reaction process, excellent regio- and stereoselectivities are observed.