Single-Step Synthesis of Cyclooctadienone Derivatives by Reaction of Alkenylcyclobutenones with Alkenyllithiums: Enhanced Reactivity of 8π Cyclization by Acetylating the Intermediary Lithium Tetraenolate
Dichlorocyclobutenone acetals, available via the cycloaddition of dichloroketene and alkynes followed by acetalization, undergo selective SN2’ attack by various nucleophiles to give a variety of functionalized cyclobutene derivatives in high yields.