Catalyst-Controlled Divergent Cycloisomerizations of N-Propargyl Indoles

Herein, a new series of catalyst-controlled divergentcycloisomerizationsof indole-tethered alkynes was developed utilizing readily available,versatile, and flexible N-propargyl indoles as substratesand BrettPhosAuNTf(2) and PtCl4 as catalysts,where the chemodivergency was attributed to both the steric and electronicnature of the catalysts. A broad spectrum of N-propargylindoles could be employed in this protocol, enabling the divergentsynthesis of a library of 9H-pyrrolo[1,2-a]indoles and 4H-pyrrolo[3,2,1-ij]quinolines. Moreover, the reactions could be performedat mmol scales.

Automated summary

A new series of catalyst-controlled divergent cycloisomerizations of indole-tethered alkynes was developed using N-propargyl indoles as substrates and BrettPhosAuNTf(2) and PtCl4 as catalysts. The chemodivergence was attributed to the steric and electronic nature of the catalysts. A wide range of N-propargyl indoles could be used in this protocol, allowing for the divergent synthesis of 9H-pyrrolo[1,2-a]indoles and 4H-pyrrolo[3,2,1-ij]quinolines. The reactions could also be performed at mmol scales.