Organocatalytic asymmetric [3 + 3] annulations of 3-carboxamide oxindoles with β,γ-unsaturated α-keto esters: facile access to chiral spiro-δ-lactam oxindoles

A novel strategy for the organocatalytic asymmetric synthesis of spiro- δ -lactam oxindoles was developed via a [3 + 3] annulation of 3-carboxamide oxindoles and β , γ -unsaturated α -keto esters with excellent diastereoselectivities and enantioselectivities.