Synthesis of All Ring Sizes of Medium-Sized Heterocycles Bridged Biaryls via VQM-Enabled Diversity-Oriented Synthetic Strategy

Herein, for the first time, the controllable, accurate, and diverse synthesis of all ring sizes of medium-sized (8- to 11-membered) indole-derived bridged biaryls has been realized by using ingeniously designed o-alkynylnaphthols that feature cyclic amines with adjustable ring sizes. The transformation may proceed through a DBN-mediated in-situ generation of vinylidene ortho-quinone methides/indole-ring formation/ring expansion cascade sequence, which is characterized by acceptable to excellent yields and good functional group tolerance.