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Hydroboration of arynes with N-heterocyclic carbene boranes
Tsuyoshi Taniguchi1, Dennis P Curran
1School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan). tsuyoshi@p.kanazawa-u.ac.jp.
Abstract:
Arynes were generated in situ from ortho-silyl aryl triflates and fluoride ions in the presence of stable N-heterocyclic carbene boranes (NHC-BH3). Spontaneous hydroboration ensued to provide stable B-aryl-substituted NHC-boranes (NHC-BH2Ar). The reaction shows good scope in terms of both the NHC-borane and aryne components and provides direct access to mono- and disubstituted NHC-boranes. The formation of unusual ortho regioisomers in the hydroboration of arynes with an electron-withdrawing group supports a hydroboration process with hydride-transfer character.
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