Electron Paramagnetic Resonance and Computational Studies of Radicals Derived from Boron-Substituted N-Heterocyclic Carbene Boranes
作者:John C. Walton、Malika Makhlouf Brahmi、Julien Monot、Louis Fensterbank、Max Malacria、Dennis P. Curran、Emmanuel Lacôte
DOI:10.1021/ja2038485
日期:2011.7.6
with aryl and alkylsubstituents on boron were prepared, and their radical chemistry was explored by electron paramagnetic resonance (EPR) spectroscopy and calculations. Hydrogen atom abstraction from NHC-BH(2)Ar groups produced boryl radicals akin to diphenylmethyl with spin extensively delocalized across the NHC, BH, and aryl units. All of the NHC-B·HAr radicals studied abstracted Br-atoms from alkyl
A number of tetraaryltin compounds, Ar4Sn (where Ar = phenyl, o- and p-tolyl, and p-chlorophenyl) and triphenyltin compounds, Ph3SnX (where X = Cl, H, OH, OCOCH3, and OCOCF3) have been treated with diborane in tetrahydrofuran. Transmetallation occurs in which one or more aryl groups are transferred to boron. The organoboron intermediates give phenols upon oxidation and boronic and borinic acids upon
A versatile new method for the preparation of NHC boranes starting from two stable, readily available reactants―an heterocyclic salt and an amine or phosphine−borane―is reported. It uses a Lewis base exchange at boron and provides easy access to new NHC boranes, in particular B-substituted borane ones.