Iodine(III)-Enabled Distal C–H Functionalization of Biarylsulfonanilides

Here we report a metal-free C–N coupling reaction for carbazole synthesis by distal (-meta) C–H bond functionalization. Nitrenium ion, a potential synthetic intermediate, was generated in situ from reactions of iodine­(III) reagents and biarylsulfonanilides. Following, nitrenium ions were used for intramolecular dehydrogenative C–N coupling reactions via 1,2-alkyl (methyl or ethyl) migration by the expense of C–H bond functionalization at the distal position toward synthesis of 1,2,4-trialkyl-substituted carbazoles. The iodine­(III) condition was either maintained by using a stoichiometric amount of phenyliodine diacetate (PIDA) or in-situ generated from iodobenzene (PhI)–meta-chloroperbenzoic acid (mCPBA) combination.