Chemodivergent Synthesis of Fused Indole and Spirocyclic Indoline Through Solo-Coordination-Vacant Ir(III) Pincer Complex-Catalyzed Acylnitrenoid Transfer.

Despite the medicinal importance of fused indoles and spirocyclic indolines, a divergent synthesis of these two frameworks from identical starting materials remains elusive. Herein, we report a solo-coordination-vacant Ir(III) pincer complex-catalyzed chemodivergent annulation of indole-derived dioxazolones that selectively constructs either scaffold by simply modulating reaction conditions. The transformation proceeds via a common iridium-nitrenoid intermediate that diverges through either a 1,2-alkyl migration or hydride-transfer pathway, delivering both classes of products with high efficiency. Notably, the spirocyclization pathway operates at an exceptionally low catalyst loading of 0.01 mol%, affording a remarkable turnover number up to 6800. This work not only fills the gap in divergent access to these two medicinally relevant heterocycles but also demonstrates the synthetic potential of nitrenoid intermediates in enabling tunable indole dearomatization.