K3PO4‐Promoted Cycloannulation of (E)‐β‐Iodovinyl Sulfones with ortho‐Hydroxy‐Chalcones/Cinnamates for the Synthesis of 2,3,4‐Trisubstituted 4H‐Benzopyran Derivatives

Abstract K 3 PO 4 ‐mediated cycloannulation of ( E )‐β‐iodovinyl sulfones with ortho ‐hydroxy chalcones/ ortho ‐hydroxy cinnamates has been realized to access 2,3,4‐trisubstituted‐4 H ‐benzopyran derivatives. A metal‐free tandem oxa‐Michael addition and cycloannulation allows the diversity‐oriented synthesis of the corresponding 3‐sulfonyl‐4 H ‐benzopyrans in good to high yields. More importantly, one‐pot three‐component reaction between ( E )‐β‐iodovinyl sulfones, 2‐hydroxybenzaldehydes, and phosphonium ylides has been established for the synthesis of 4 H ‐chromene derivatives in moderate to good yields. Notably, this metal‐free process features a broad substrate scope and easy elaboration into numerous multifaceted chromene products, including bioactive estrone‐derivative. The present protocol is sustainable at the gram scale reactions, and post‐synthetic applications were also demonstrated. A plausible mechanism is also presented on the basis of existing experimental results. magnified image