Late-stage diversification of indole skeletons through nitrogen atom insertion

Advances in the field of late-stage functionalization have expedited lead-structure discovery and established new opportunities to access valuable molecules. Although many peripheral late-stage transformations, mainly focusing on C–H functionalizations, have been reported, reliable strategies to directly edit the core skeleton of lead compounds have remained scarce. Late-stage remodeling strategies of widely encountered and pharmaceutically relevant scaffolds, such as indoles, would offer enormous potential to expand accessible chemical space. Herein, we report the skeletal editing of indoles through nitrogen atom insertion, accessing their corresponding quinazoline or quinoxaline bioisosteres via trapping of an electrophilic nitrene species generated from ammonium carbamate and hypervalent iodine. This unique reactivity is unlocked through the strategic use of a silyl group which acts as a reactivity-controlling element to suppress the inherent nucleophilicity of the nitrogen in indoles. Importantly, the utility of this highly functional group-tolerant methodology in the context of late-stage skeletal editing of several commercial drugs is demonstrated.