Organocatalytic Diels–Alder Reaction of 2-Vinylindoles with Methyleneindolinones: An Efficient Approach to Functionalized Carbazolespirooxindoles

An unprecedented asymmetric Diels–Alder reaction of 2-vinylindoles with methyleneindolinones has been disclosed. Under bifunctional organocatalysis by cinchona-derived squaramide catalyst, a series of diversely functionalized carbazolespirooxindole derivatives bearing three contiguous stereocenters are rapidly constructed under mild conditions (48–90% yields, up to >20:1 dr and 99% ee).