%0 Journal Article
%@ 0002-7863
%A Pan, X
%A Lacôte, E
%A Lalevée, J
%A Curran, DP
%D 2012
%F pittir:17951
%J Journal of the American Chemical Society
%N 12
%P 5669 - 5674
%T Polarity reversal catalysis in radical reductions of halides by N-heterocyclic carbene boranes
%U http://d-scholarship-dev.library.pitt.edu/17951/
%V 134
%X Otherwise sluggish or completely ineffective radical reductions of alkyl and aryl halides by N-heterocyclic carbene boranes (NHC-boranes) are catalyzed by thiols. Reductions and reductive cyclizations with readily available 1,3-dimethylimidazol-2-ylidene borane and a water-soluble triazole relative are catalyzed by thiophenol and tert-dodecanethiol [C 9H 19C(CH 3) 2SH]. Rate constants for reaction of the phenylthiyl (PhS•) radical with two NHC-boranes have been measured to be ∼10 8 M -1 s -1 by laser flash photolysis experiments. An analysis of the available evidence suggests the operation of polarity reversal catalysis. © 2012 American Chemical Society.