Substituent and Lewis Acid Promoted Dual Behavior of Epoxides towards [3+2]‐Annulation Reactions with Donor‐Acceptor Cyclopropanes: Synthesis of Substituted Cyclopentane and Tetrahydrofuran

Substituent and Lewis acid promoted generation of functionalized enolates from epoxides is developed. Divergent attack of the enolate on donor‐acceptor cyclopropanes, i.e. C‐attack or O‐attack depending upon substituents present in both reacting partners, produced different products. C‐attack gave functionalized cyclopentane derivatives, whereas O‐attack furnished tetrahydrofuran derivatives through [3+2]‐annulation reactions. Moreover, to increase the utility of our method, synthesized diastereomeric cyclopentane derivatives were converted into synthetically useful cyclopentene and cyclopentanone analogs.