EPR studies of the generation, structure, and reactivity of n-heterocyclic carbene borane radicals

Journal of the American Chemical Society
John C WaltonDennis P Curran

Abstract

N-Heterocyclic carbene boranes (NHC-boranes) are a new "clean" class of reagents suitable for reductive radical chain transformations. Their structures are well suited for their reactivity to be tuned by inclusion of different NHC ring units and by appropriate placement of diverse substituents. EPR spectra were obtained for the boron-centered radicals generated on removal of one of the BH(3) hydrogen atoms. This spectroscopic data, coupled with DFT computations, demonstrated that the NHC-BH(2)* radicals are planar pi-delocalized species. tert-Butoxyl radicals abstracted hydrogen atoms from NHC-boranes more than 3 orders of magnitude faster than did C-centered radicals, although the rate decreased markedly for sterically shielded NHC-BH(3) centers. Combinations of two NHC-boryl radicals afforded 1,2-bis-NHC-diboranes at rates which also depended strongly on steric shielding. The termination rate increased to the diffusion-controlled limit for sterically unhindered NHC-boryls. Bromine atoms were rapidly transferred to imidazole-based NHC-boryl radicals from alkyl, allyl, and benzyl bromides. Chlorine-atom abstraction was, however, much less efficient and only observed for sterically unhindered NHC-boryls reacting with allylic and...Continue Reading

References

Jun 1, 1994·Journal of Magnetic Resonance. Series B·D R Duling
Aug 16, 2003·The Journal of Organic Chemistry·Kazuaki TakamiKoichiro Oshima
Sep 25, 2007·Journal of the American Chemical Society·Yuzhong WangGregory H Robinson
Jul 10, 2008·Journal of the American Chemical Society·Shau-Hua UengDennis P Curran
Jul 18, 2009·Journal of the American Chemical Society·Shau-Hua UengDennis P Curran
Oct 6, 2009·Organic Letters·Julien MonotEmmanuel Lacôte
May 8, 2010·Chemical Communications : Chem Comm·Thomas K WoodMasood Parvez

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Citations

Jan 5, 2014·Chemical Reviews·Fabrice DénèsPhilippe Renaud
Oct 29, 2015·The Journal of Organic Chemistry·Tao LiuZhihua Sun
Sep 4, 2015·The Journal of Organic Chemistry·Sean GardnerDennis P Curran
Oct 7, 2016·The Journal of Organic Chemistry·Guillaume Tambutet, Yvan Guindon
Feb 28, 2017·Chemical Reviews·Binshen WangGuohua Gao
Apr 13, 2017·Journal of the American Chemical Society·Shi-Chao RenYi-Feng Wang
May 26, 2017·Organic Letters·Vyacheslav I SupranovichAlexander D Dilman
Dec 5, 2015·Angewandte Chemie·Yong-Qiang ZhangAndreas Gansäuer
Dec 21, 2016·Angewandte Chemie·Miguel F Silva ValverdeMatthias Tamm
Jul 23, 2015·Dalton Transactions : an International Journal of Inorganic Chemistry·Rajendra S GhadwalGernot Frenking
Jun 18, 2017·Science·Alexander FawcettVarinder K Aggarwal
Feb 16, 2018·Angewandte Chemie·Nengneng ZhouChengjian Zhu
May 31, 2018·Angewandte Chemie·Masaki ShimoiTsuyoshi Taniguchi
Jun 22, 2018·Angewandte Chemie·Daniel SubervieEmmanuel Lacôte
Jul 27, 2018·Chemical Communications : Chem Comm·Dipak Kumar RoyHolger Braunschweig
Sep 8, 2011·Angewandte Chemie·Dennis P CurranEmmanuel Lacôte
Jul 31, 2018·Chemistry : a European Journal·Youngsuk Kim, Eunsung Lee
Apr 24, 2010·Nature·Kyoko Nozaki
Sep 21, 2010·Angewandte Chemie·Julien MonotEmmanuel Lacôte
Sep 30, 2010·Chemistry : a European Journal·Jacques LalevéeJean-Pierre Fouassier
Nov 27, 2010·Angewandte Chemie·Vincent LavalloRobert H Grubbs
Jul 12, 2011·Chemical Science·David MartinGuy Bertrand
Jul 24, 2013·Chemical Science·Caleb D MartinGuy Bertrand
Jun 18, 2019·Chemistry : a European Journal·Xavier FrogneuxSophie Carenco
Dec 10, 2019·Angewandte Chemie·Wenlong YangRobert J Gilliard
Jun 12, 2014·Angewandte Chemie·Philipp BissingerShun Sugawara
Apr 23, 2020·Chemical Communications : Chem Comm·Dominic PrieschlHolger Braunschweig
Mar 7, 2020·Chemistry : a European Journal·Ahmad MasarwaAlexander Shames
Mar 10, 2020·Chemistry : a European Journal·Ryan Andrews, Douglas Wade Stephan
Aug 4, 2020·Dalton Transactions : an International Journal of Inorganic Chemistry·Andreas HockUdo Radius
Feb 9, 2012·Angewandte Chemie·Dennis P CurranEmmanuel Lacôte
Feb 18, 2012·Angewandte Chemie·Andreas GansäuerMaurice van Gastel
Sep 25, 2012·Dalton Transactions : an International Journal of Inorganic Chemistry·Andrey SolovyevDennis P Curran
Feb 16, 2012·Angewandte Chemie·Holger BraunschweigJohannes Wahler
Apr 9, 2014·Angewandte Chemie·Philipp BissingerAlfredo Vargas
Jun 30, 2015·Angewandte Chemie·Amos J RosenthalDidier Bourissou
Apr 16, 2011·Angewandte Chemie·Philipp BissingerThomas Kupfer

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