Oxidative Generation of Boron-Centered Radicals in Carboranes
Harrison A. Mills, Joshua L. Martin, Arnold L. Rheingold, Alexander M. Spokoyny
Abstract
We report the first indirect observation and use of boron vertex-centered carboranyl radicals generated by the oxidation of modified carboranyl precursors. These radical intermediates are formed by the direct oxidation of a B–B bond between a boron cluster cage and an exopolyhedral boron-based substituent (e.g., −BF3K, −B(OH)2). The in situ generated radical species are shown to be competent substrates in reactions with oxygen-based radicals, dichalcogenides, and N-heterocycles, yielding the corresponding substituted carboranes containing B–O, B–S, B–Se, B–Te, and B–C bonds. Remarkably, this chemistry tolerates various electronic environments, providing access to facile substitution chemistry at both electron-rich and electron-poor B–H vertices in carboranes.