Organocatalytic enantioselective desymmetrization of cyclic enones via phosphine promoted [3+2] annulations

Phosphine catalyzed enantioselective [3+2] cyclizations on 4-substituted 2,6-diarylidenecyclohexanones and 2,4-diarylidene-bicyclo[3.1.0]hexan-3-ones take place with high diastereo- and enantioselectivity levels. The process affords spirocyclic compounds with excellent stereochemical control of up to five stereogenic centres.