Cycloisomerization of enynones by aluminum halides: construction of bicyclo[3.1.0]hexanes by introducing halides

Alkyne pi-bond activation by transition metal complexes has been well studied for cycloisomerization of enynes into bicyclo[3.1.0]hexanes, which can allow the introduction of carbon and oxygen functional groups concomitant with the construction of the core structures. However, the cycloisomerization of enynones through the activation of carbonyl groups into bicyclo[3.1.0]hexanes has not been achieved. Herein, we report the aluminum halide-mediated cycloisomerization of 7-en-2-ynones into halogenated bicyclo[3.1.0]hexanes.