Asymmetric Cyclopentannulation of Cyclic Enones with a Chiral 1,3‐Dipole Equivalent

A highly selective cis-fusion is observed for the reaction of the chiral 1,3-dipole equivalent 1 with cyclic enone 2 to form the bicyclic cyclopentenone 3. This multistep method, which does not require isolation of intermediates, is conceptually analogous to the Robinson annulation and should find wide applicability.