Icosahedral carboranes, (C2B10H12) are a family of synthetically versatile, robust, 3D aromatic cluster molecules. Their utility as small molecule pharmacophores1, polymer functional groups2, and supramolecular framework linkers3 drives the need for carborane-based building blocks. However, compared to aryl substrates, the utility of carboranes is restricted by their relatively underdeveloped substitution chemistry. Metal-catalyzed cross-coupling provides powerful synthetic routes for new molecules, yet the development of carborane cross-coupling has lagged far behind their aromatic hydrocarbon counterparts. Carborane boron vertex cross-coupling has been confined to iodo-carborane derivatives. Our work shows, for the first time, that by using electron-rich, biaryl phosphine ligands, bromo-carboranes can also undergo efficient cross-coupling. The generality of bromo-carborane cross-coupling is demonstrated by using various coupling partners and carried out on several bromo-carborane positional isomers. This new cross-coupling approach opens new synthetic routes toward developing new functionalized carborane building blocks. 1. Goswami, L. N.; Khan, A. A.; Jalisatgi, S. S., Chem. Commun., 2014, 50, 5793-5795. 2. Peterson, J. J.; Werre, M.; Simon, Y. C.; Coughlin, E. B.; Carter, K. R., Macromolecules, 2009, 42, 8594-8598. 3. Clingerman et al., Chem Comm, 2015, 51, 6521-6523.

Selective vertex cross-coupling of bromo-carboranes using electron-rich phosphine ligands

251st National Meeting (2016)

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