Metal-Free [3 + 2 + 1]/[2 + 2 + 1] Biscyclization: Stereospecific Construction with Concomitant Functionalization of Indolizin-5(1H)‑one

A metal-free [3 + 2 + 1]/[2 + 2 + 1] biscyclization strategy has been developed for the stereospecific construction with concomitant derivation of biologically significant indolizin-5­(1H)-ones from simple and commercial starting materials. The transformations are notable because they can yield five new σ bonds and six stereocenters including a quaternary carbon center in a single operation.