2788-41-2Relevant academic research and scientific papers
Metal-Free sp2-C-H Borylation as a Common Reactivity Pattern of Frustrated 2-Aminophenylboranes
Chernichenko, Konstantin,Lindqvist, Markus,Kótai, Bianka,Nieger, Martin,Sorochkina, Kristina,Pápai, Imre,Repo, Timo
, p. 4860 - 4868 (2016)
C-H borylation is a powerful and atom-efficient method for converting affordable and abundant chemicals into versatile organic reagents used in the production of fine chemicals and functional materials. Herein we report a facile C-H borylation of aromatic and olefinic C-H bonds with 2-aminophenylboranes. Computational and experimental studies reveal that the metal-free C-H insertion proceeds via a frustrated Lewis pair mechanism involving heterolytic splitting of the C-H bond by cooperative action of the amine and boryl groups. The adapted geometry of the reactive B and N centers results in an unprecedentently low kinetic barrier for both insertion into the sp2-C-H bond and intramolecular protonation of the sp2-C-B bond in 2-ammoniophenyl(aryl)- or -(alkenyl)borates. This common reactivity pattern serves as a platform for various catalytic reactions such as C-H borylation and hydrogenation of alkynes. In particular, we demonstrate that simple 2-aminopyridinium salts efficiently catalyze the C-H borylation of hetarenes with catecholborane. This reaction is presumably mediated by a borenium species isoelectronic to 2-aminophenylboranes.
Use of Simple Test Reactions to Characterise the Catalytic Activity of a Commercial CoO-MoO3-Al2O3 Catalyst
John, Christopher S.,Williamson, James G.,Kennedy, Lois V. F.,Tyler, J. Kelvin
, p. 1356 - 1365 (2007/10/02)
Exchange of thiophene with D2 and reactions of deuterium-labelled propene and isobutene, followed using a combination of mass spectometry and microwave spectroscopy, have been used to characterise the catalytic nature of a commercial CoO-MoO3-Al2O3 (CMA) catalyst.The results indicate that the activity of partially sulphided CMA, produced by exposure to H2S or by hydrodesulphurization (h.d.s.) of ethanethiol, closely resembles that of unsupported MoS2.Thus, sulphided-CMA shows high selectivity/activity for exchange of the α hydrogens in thiophene and catalyses double bond migration in propene through half-hydrogenated intermediates, activity characteristic of MoS2, whereas oxide-CMA is much less active for α exchange and shows Lewis acid type activity for the latter reaction.It appears that a CMA catalyst during h.d.s. may usefully be described as "dual-functional", with MoS2 supported on, and stabilised by, an acidic support.
