Tf 2 O‐Mediated Three‐Component Cascade Cyclization of Pyridyl‐Enaminones, Cyclopropanols, and DABCO·(SO 2 ) 2 : Access to γ‐Keto Azarylsulfones

An oxidant‐ and transition‐metal‐free Tf 2 O‐mediated three‐component cascade cyclization of pyridyl‐enaminones, cyclopropanols, and DABCO·(SO 2 ) 2 is described. A variety of 1‐aryl‐ and 1‐alkyl‐substituted cyclopropanols, as well as diverse pyridyl‐enaminones, participated smoothly in this transformation to deliver the corresponding γ‐keto indolizinyl sulfones in 41%–93% yields under mild conditions. This reaction features operational simplicity, broad functional group tolerance, and readily available starting materials. Moreover, this protocol represents the first example for the construction of γ‐keto azarylsulfones via a multicomponent SO 2 ‐insertion strategy.