Iridium-catalyzed [(5+1)−1] annulation of pyridinium 1,4-zwitterionic thiolates and sulfoxonium ylides: a versatile platform to indolizines

An efficient synthesis of indolizines from pyridinium 1,4-zwitterionic thiolates and sulfoxonium ylides via a formal [(5+1)-1] pathway has been demonstrated. This reaction process involved an iridium(III)-catalyzed (5+1) annulation, oxidation, and ring-contraction/desulfuration. This protocol featured mild conditions, broad substrate scope, and functional-group compatibility, and could be applied in late-stage modification of multiple bioactive molecules. In addition, scale-up synthesis, related applications, and preliminary mechanistic studies were also accomplished.