- Steric Properties of N-Heterocyclic Carbenes affect the Performance of Electronic Probes
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Electronic probes of ligands, particularly carbenes, are widely used in assessing electronic properties; the results inform the selection of a ligand for a given application. As such, it is important to ensure the data obtained is reliable and unaffected by other factors, such as the steric bulk of the ligand. The effects of such steric factors on two commonly used electronic probes (based on palladium and selenium) are investigated here, with the selenium adduct found to be particularly sensitive. It is hoped that this serves as a cautionary tale to always critically evaluate what a probe is measuring.
- Barnett, Christopher,Cole, Marcus L.,Harper, Jason B.
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p. 4954 - 4958
(2021/12/02)
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- A closer look at the reactivity between N-heterocyclic carbenes and fluoroalkenes
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The fundamental reactivity leading to N-heterocyclic fluoroalkene adducts is explored in detail, featuring a total of 15 N-heterocyclic carbenes (NHCs) with various electronic and steric environments. The activity of these carbenes towards tetrafluoroethylene (TFE), hexafluoropropene (HFP), trifluoroethylene (HTFE) and vinylidene fluoride (VDF) is assessed in THF and toluene. Attempts were made to correlate the observed reactivity with electronic (Tolman Electronic Parameters) and steric (% buried volume) parameters unique to each NHC, but a trend has yet to be fully determined. However, the unique steric constraints of a cyclic (alkyl)(amino)carbene (CAAC) were shown to modify the initial point of nucleophilic attack on HTFE, providing selective transformation to a different adduct than has been observed to date with all reactions involving this fluoroalkene.
- Leclerc, Matthew C.,Da Gama, Jason G.,Gabidullin, Bulat M.,Baker, R. Tom
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- Regioselective hydrocarbamoylation of 1-alkenes
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Nickel/Lewis acid cooperative catalysis derived from [Ni(cod)2], AlEt3, and N-heterocyclic carbene (NHC) effects highly regioselective hydrocarbamoylation of 1-alkenes. Variously substituted formamides and 1-alkenes can be employed to give a range of linear alkanamides regioselectively.
- Miyazaki, Yosuke,Yamada, Yuuya,Nakao, Yoshiaki,Hiyama, Tamejiro
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supporting information; experimental part
p. 298 - 300
(2012/05/20)
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- Construction of tetrasubstituted carbon by an organocatalyst: Cyanation reaction of ketones and ketimines catalyzed by a nucleophilic N-heterocyclic carbene
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A method for cyanation reaction of ketones and ketimines having lower reactivity than aldehydes and aldimines with TMSCN in the presence of N-heterocyclic carbene prepared from 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride and potassium tert-butoxide
- Fukuda, Yoshimasa,Kondo, Kazuhiro,Aoyama, Toyohiko
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p. 2649 - 2652
(2008/02/04)
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