I₂‐Promoted Oxidative Annulation of Deoxybenzoin‐Chalcone Adduct: Temperature‐Controlled Access to Tetrasubstituted 2,3‐trans‐Dihydrofurans and Furans

Tetrasubstituted 2,3‐ trans ‐dihydrofuran and furan are important heterocyclic scaffolds in natural product, bioorganic and medicinal chemistry as well as in material science. The synthesis of both of these heterocycles starting from common and readily available starting materials are challenging. We found that in situ generated deoxybenzoin‐chalcone Michael adducts underwent oxidative annulation upon heating with molecular iodine in DMSO to provide selectively 2,3‐ trans ‐dihydrofurans at 80 °C and furans at 120 °C.