Construction of Fused‐oxa‐[n.2.1] Skeletons by Tandem Intramolecular [3+2] Cycloaddition/O‐H Insertion/Ester Exchange of Cyclopropanes with Diazocarbonyls

A Lewis acid promoted tandem reaction of intramolecular [3+2] cycloaddition/O−H insertion/ester exchange of cyclopropanes with diazocarbonyls is reported to synthesize fused‐oxa‐[n.2.1] skeletons, which tolerates both aryl and alkyl diazocarbonyl substrates. A wide variety of fused‐oxa‐[n.2.1] skeletons were efficiently constructed.