N-Heterocyclic Carbene Non-Innocence in the Catalytic Hydrophosphination of Alkynes

William J. M. Blackaby; Samuel E. Neale; Connie J. Isaac; Sara Sabater; Stuart A. Macgregor; Michael K. Whittlesey

doi:10.1002/cctc.201900220

N-Heterocyclic Carbene Non-Innocence in the Catalytic Hydrophosphination of Alkynes

William J. M. Blackaby, Samuel E. Neale, Connie J. Isaac, Sara Sabater, Stuart A. Macgregor^*, Michael K. Whittlesey

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

Studies on alkyne hydrophosphination employing nickel-NHC catalysts (NHC=N-heterocyclic carbene) revealed that the free N-alkyl substituted NHCs themselves were catalytically active. DFT calculations showed the mechanism involves the NHC acting as a Brønsted base to form an imidazolium phosphide species which then undergoes rate-limiting nucleophilic attack at the terminal alkyne carbon. This mechanism explains the preference seen experimentally for reactions with aryl substituted phosphines and alkynes, while the rearrangements of the alkenyl anion formed upon P−C bond formation account for the observation of both Z- and E-regioisomers of the products.

Original language	English
Pages (from-to)	1893-1897
Number of pages	5
Journal	ChemCatChem
Volume	11
Issue number	7
Early online date	20 Feb 2019
DOIs	https://doi.org/10.1002/cctc.201900220
Publication status	Published - 4 Apr 2019

Keywords

density functional calculations
homogeneous catalysis
hydrophosphination
N-heterocyclic carbene
reaction mechanisms

ASJC Scopus subject areas

Catalysis
Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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This is the peer reviewed version of the following article: W. J. M. Blackaby, S. E. Neale, C. J. Isaac, S. Sabater, S. A. Macgregor, M. K. Whittlesey, ChemCatChem 2019, 11, 1893, which has been published in final form at https://doi.org/10.1002/cctc.201900220 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
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abstract = "Studies on alkyne hydrophosphination employing nickel-NHC catalysts (NHC=N-heterocyclic carbene) revealed that the free N-alkyl substituted NHCs themselves were catalytically active. DFT calculations showed the mechanism involves the NHC acting as a Br{\o}nsted base to form an imidazolium phosphide species which then undergoes rate-limiting nucleophilic attack at the terminal alkyne carbon. This mechanism explains the preference seen experimentally for reactions with aryl substituted phosphines and alkynes, while the rearrangements of the alkenyl anion formed upon P−C bond formation account for the observation of both Z- and E-regioisomers of the products.",

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KW - density functional calculations

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N-Heterocyclic Carbene Non-Innocence in the Catalytic Hydrophosphination of Alkynes

Abstract

Keywords

ASJC Scopus subject areas

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