Strain-Release-Driven Alder-Ene Reaction of Bicyclo[1.1.0]butanes with β-Fluoroalkyl-α,β-Unsaturated Ketones.

The Alder-ene reaction of the C-C bond in bicyclo[1.1.0]butanes would provide a unique and efficient synthesis route for cyclobutene frameworks. Herein, we report a regio- and diastereoselective Alder-ene reaction of bicyclo[1.1.0]butanes with β-fluoroalkyl-α,β-unsaturated ketones, giving a wide variety of cyclobutenes with two contiguous centers and diene products. The reaction features atoms and step economies and exhibits broad substrate scope. Several downstream transformations of these cyclobutenes were performed.