An Organocatalytic [3+2] Cyclisation Strategy for the Highly Enantioselective Synthesis of Spirooxindoles

Power of P: Phosphine-promoted [3+2] annulation reactions between electron-poor allenes and 3-arylidene indolin-2-ones afford a new organocatalytic strategy for the synthesis of the spirocyclic core of oxindolic cyclopentanes (see scheme). Asymmetric variants of these reactions have been implemented by using chiral catalysts, giving very high levels of asymmetric induction.