22608-37-3Relevant articles and documents
Replacing C6F5 groups with Cl and H atoms in frustrated Lewis pairs: H2 additions and catalytic hydrogenations
Chernichenko,Kótai,Nieger,Heikkinen,Pápai,Repo
, p. 2263 - 2269 (2017)
2-(Dialkylamino)phenylboranes containing the BXZ group, where X, Z = C6F5, Cl, and H, were prepared in a few synthetic steps and demonstrated the cleavage of H2 under mild conditions. Depending on the nature of the dialkylamino group, X, and Z, the stability of the produced zwitterionic H2 adducts varies from isolated solids indefinitely stable in an inert atmosphere to those quickly equilibrating with the initial aminoborane and H2. Using a combined experimental/computational approach on a series of isostructural aminoboranes (dialkylamino = 2,2,6,6-tetramethylpiperid-1-yl), it was demonstrated that the electronegativity and the steric effect of the substituents generally follow the trend C6F5 ～ Cl ? H. This observation is useful for designing new FLPs for practical applications. As an example, we demonstrated the hydrogenation of alkynes to cis-alkenes under mild conditions that was catalyzed by a chloro-analogue of the C6F5-substituted aminoborane developed previously. The presence of a BHCl group in the aminochloroboranes or in their H2 adducts features facile redistribution of the H and Cl atoms and the formation of polychloro and polyhydrido species.
Aluminium-Catalyzed C(sp)?H Borylation of Alkynes
Willcox, Dominic R.,De Rosa, Daniel M.,Howley, Jack,Levy, Abigail,Steven, Alan,Nichol, Gary S.,Morrison, Carole A.,Cowley, Michael J.,Thomas, Stephen P.
supporting information, p. 20672 - 20677 (2021/08/20)
Historically used in stoichiometric hydroalumination chemistry, recent advances have transformed aluminium hydrides into versatile catalysts for the hydroboration of unsaturated multiple bonds. This catalytic ability is founded on the defining reactivity of aluminium hydrides with alkynes and alkenes: 1,2-hydroalumination of the unsaturated π-system. This manuscript reports the aluminium hydride catalyzed dehydroborylation of terminal alkynes. A tethered intramolecular amine ligand controls reactivity at the aluminium hydride centre, switching off hydroalumination and instead enabling selective reactions at the alkyne C?H σ-bond. Chemoselective C?H borylation was observed across a series of aryl- and alkyl-substituted alkynes (21 examples). On the basis of kinetic and density functional theory studies, a mechanism in which C?H borylation proceeds by σ-bond metathesis between pinacolborane (HBpin) and alkynyl aluminium intermediates is proposed.
Stereostructure and thermodynamic stability of atropisomers of ortho-substituted 2,2′-diaryl-1,1′-binaphthalenes
Ehn, Marcel,Vassilev, Nikolay Georgiev,Kasak, Peter,Horvath, Branislav,Filo, Juraj,Mereiter, Kurt,Rakovsky, Erik,Putala, Martin
, p. 1303 - 1311 (2013/11/19)
A series of ortho-substituted 2,2′-aryl-1,1′-binaphthalenes were prepared via Negishi arylation of 2,2′-diiodo-1,1′- binaphthalene in good to high yields (65-95%) as an equilibrium mixtures of up to three atropisomers (unlike,unlike, like,unlike, and like,like). Thermodynamic stability parameters of the atropisomers were evaluated from VT NMR spectra by regression analysis. The DFT parameters calculated using CAM-B3LYP functional comprising solvent permittivity were, apart from the toluene solution, which was expected to interact with the aromatic solute, in qualitative agreement with the experimental values. In the case of the ditolyl derivative, the population of the atropisomers was confirmed by CD spectroscopy via comparison with the population-weighted averaged spectrum computed using the M06 functional. X-ray structure analyses of particular atropisomers of the dianisyl, dianilinyl, and dinaphthyl derivatives are also presented and discussed.
Ortho-lithiations reassessed: The advantages of deficiency catalysis in hydrocarbon media
Slocum,Reinscheld, Thomas K.,White, Christopher B.,Timmons, Michael D.,Shelton, Philip A.,Slocum, Matthew G.,Sandlin, Rebecca D.,Holland, Erica G.,Kusmic, Damir,Jennings, John A.,Tekin, Kristen C.,Nguyen, Quang,Bush, Steven J.,Keller, Julia M.,Whitley, Paul E.
, p. 1674 - 1686 (2013/05/08)
Hydrocarbon media based metalation procedures involving "deficiency catalysis" are described for the ortho-lithiation of anisole (A), p-chloroanisole (p-ClA), o-, m-, p-methylanisoles (o-, m-, p-MA), the three dimethoxybenzenes (DMB's), dimethylaniline (DMA), dimethybenzylamine (DMBA), m-methoxydimethylaniline (m-MeODMA), and tetramethyl-p-phenylenediamine (p-TMPDA). These procedures involve certain mechanistic considerations, which must be fine-tuned to maximize the extent of metalation (EoM). Our working hypothesis is that a controlled deoligomerization of the n-BuLi hexamer found in hydrocarbon media will afford a "sweet spot" of deoligomerization such that a maximally efficient metalation medium can be formed. In many cases, a substoichiometric ratio of equivalent TMEDA to n-BuLi is 0.1-0.2:1.0, but certain substrates suffer multiple sites of metalation under these conditions, so different promoted hydrocarbon media systems incorporating measured equivalents of an ether have been formulated. This paper represents the summary of our successful efforts to render ortho-lithiations safer, greener, and more atom-economical by use of hydrocarbon solvent media. EoM's of 11 of the 12 substrates under these atom-economical conditions range from 87 to 97%.
Hydrogen activation by 2-boryl-N,N-dialkylanilines: A revision of Piers' ansa-aminoborane
Chernichenko, Konstantin,Nieger, Martin,Leskelae, Markku,Repo, Timo
supporting information; experimental part, p. 9029 - 9032 (2012/09/08)
Two 2-[bis(pentafluorophenyl)boryl]-N,N-dialkylanilines reported here exemplify a new class of intramolecular frustrated B/N Lewis pairs. A structure closely related to this class structure was synthesized in 2003 by Piers et al. but was unable to activate H2. The new aminoboranes can activate hydrogen at near ambient conditions; besides, one of them can hydrogenate imines and enamines in a catalytic fashion demonstrating the validity of the original Piers' approach to hydrogen activation with ansa-aminoboranes.
