Metal-Free Synthesis of Functionalized Indolizines via a Cascade Michael/S2/Aromatization Reaction of 2-Alkylazaarene Derivatives with Bromonitroolefins.

A transition metal-free domino Michael/S2/aromatization annulation of 2-pyridylacetates with bromonitroolefins has been developed. A wide range of substrates containing various substituted groups was compatible with the present methodology and afforded functionalized indolizines with moderate to excellent yield (up to 99% yield). In addition, the potential practicality of the method stood out through scale-up reactions and further transformations to other valuable compounds. In our view, this study is an essential complement for the rapid construction of indolizine derivatives through a metal-free strategy.