Diazomethyl-λ3-iodane meets aryne: Dipolar cycloaddition and C-to-N iodane shift leading to indazolyl-λ3-iodanes

Abstract

Diazomethyl-λ³-iodanes have recently emerged as carbyne equivalents in organic synthesis, enabling the construction of multi-substituted carbon centers through strategic sequential activation of the diazo and iodane functional groups. Distinct from such reaction modes, we report here on the reactivity of diazomethyl-λ³-iodanes as iodane-bound 1,3-dipoles toward arynes. Equipped with bis(trifluoromethyl)benzyl alcohol-based benziodoxole (BX) moiety, diazomethyl-λ³-iodanes undergo annulation with arynes generated from ortho-silylaryl triflates and cyclic diarylhalonium salts, resulting in indazolyl-λ³-iodanes through [3+2] cycloaddition and carbon-to-nitrogen iodane migration. DFT calculations reveal that diazomethyl-BX prefers [3+2] cycloaddition with aryne over aryne insertion into the carbon–iodine(III) bond (carboiodanation) and that the subsequent iodane migration proceeds through two consecutive 1,5-iodane shifts. The utility of these indazolyl-BXs as indazole-transfer agents has been demonstrated by α-functionalization of N,N-dimethylaniline derivatives.