Smiles-Truce Cascades Enable Heteroaryl Cyclopropane and Sultine Synthesis.

We describe a triple C─C bond cascade process for heteroaryl cyclopropane synthesis, through the reaction of vinyl sulfonium salts and sulfones under mild conditions. An initial conjugate addition (C─C bond 1) sets up a Smiles-Truce rearrangement (C─C bond 2), with a final 3-exo-tet ring closure (C─C bond 3) affording cyclopropanes. Serendipitously, we uncovered a novel reaction variant that affords sultines, an under-explored heterocycle with potential application as a bioisostere in medicinal chemistry.