Iridium-Catalyzed,Copper-Induced Reductive Cyclizationof NO₂‑Pyrrolarenes with CO₂ as a Single-CarbonSource

A new catalytic conversion type of nitro substrate with CO₂ as a single-carbon source is presented, wherein a great collection of azaheterocycles is generated by a newly established iridium-catalyzed, copper-induced reductive system. This catalytic procedure handily employs poly­(methylhydrosiloxane) (PMHS) as the reductant to simultaneously realize the dual reduction of the highest oxidation-state nitro and CO₂ units in one operation. Elaborate mechanistic studies illustrate the essential role of the iridium catalyst in reducing the NO₂ moiety as well as the double functions of the copper additive in the subsequent formylation and C–H cyclization steps.