Base-Promoted [3 + 3 + 1] Annulation of α-Diazo Hypervalent Iodine(III) Reagents with Sulfonium Ylides: Access to Highly Functionalized 1,3,4-Oxadiazepines

An organic base-promoted [3 + 3 + 1] annulation between α-diazo hypervalent iodine(III) reagents and sulfonium ylides has been developed, affording a novel class of highly functionalized 1,3,4-oxadiazepines under mild conditions. This method provides a versatile route for constructing these seven-membered ring systems, which are uncommon in the literature. Furthermore, the reaction can be scaled up, and the resulting product can be successfully converted into polycyclic compounds via the Diels-Alder reaction.