Mn(OAc)3-Mediated Unexpected Cycloannulative Sulfonyl Migration Cascade using (E)-β-Iodovinyl Sulfones and ortho-Alkynylphenols for Direct Synthesis of Chromene-Derived Vinyl Sulfones

Cycloannulative sulfonyl migration has received much attention; however, a carbon-to-carbon sulfonyl group shift still needs to be discovered. We hereby report a base-mediated oxa-Michael addition-elimination of (E)-β-iodovinyl sulfones with ortho-alkynylphenols, followed by cycloisomerization and unique stereoselective sulfonyl migration in one-pot, is realized under the influence of Mn(OAc)3·2H2O. A broad range of vinyl sulfone-tethered chromenes were readily accessed in moderate to high yields with good functional group compatibility. Notably, the reaction was robust at the gram scale, and postsynthetic transformations were successfully uncovered. Moreover, plausible mechanistic pathways were rationalized on the basis of existing experimental results.