Regioselective Synthesis of Substituted Arenes via Aerobic Oxidative [3 + 3] Benzannulation Reactions of α,β-Unsaturated Aldehydes and Ketones

Facile conversion of α,β-unsaturated aldehydes and ketones into highly substituted arenes via a base-mediated, completely regioselective, air-oxidative [3 + 3] benzannulation reaction with readily available 4-sulfonyl­crotonates or 1,3-bisphenyl­sulfonyl­propene is reported. The reaction can also be carried out as a one-pot, three-component operation using 4-bromo­crotonates, aryl sulfinates, and cinnamaldehyde. This open-flask, metal-free reaction does not require anhydrous solvents, proceeds under mild conditions, and uses atmospheric oxygen as the oxidant to afford high yields of the 3-(arylsulfonyl)­benzoic acid esters.