[4 + 2] Annulation of Donor–Acceptor Cyclopropanes with Acetylenes Using 1,2-Zwitterionic Reactivity

Abstract

A new process for the [4 + 2] annulation of donor-acceptor cyclopropanes with acetylenes under the effect of anhydrous GaCl₃ using 1,2-zwitterion reactivity was elaborated. The reaction opens access to substituted dihydronaphthalenes, naphthalenes, and other fused carbocycles. The direction of the reaction can be efficiently controlled by temperature.