1069-08-5Relevant academic research and scientific papers
Generation of Axially Chiral Fluoroallenes through a Copper-Catalyzed Enantioselective β-Fluoride Elimination
O'Connor, Thomas J.,Mai, Binh Khanh,Nafie, Jordan,Liu, Peng,Toste, F. Dean
supporting information, p. 13759 - 13768 (2021/09/07)
Herein we report the copper-catalyzed silylation of propargylic difluorides to generate axially chiral, tetrasubstituted monofluoroallenes in both good yields (27 examples >80%) and enantioselectivities (82-98% ee). Compared to previously reported synthetic routes to axially chiral allenes (ACAs) from prochiral substrates, a mechanistically distinct reaction has been developed: the enantiodiscrimination between enantiotopic fluorides to set an axial stereocenter. DFT calculations and vibrational circular dichroism (VCD) suggest that β-fluoride elimination from an alkenyl copper intermediate likely proceeds through a syn-β-fluoride elimination pathway rather than an anti-elimination pathway. The effects of the C1-symmetric Josiphos-derived ligand on reactivity and enantioselectivity were investigated. Not only does this report showcase that alkenyl copper species (like their alkyl counterparts) can undergo β-fluoride elimination, but this elimination can be achieved in an enantioselective fashion.
Systematic Study of the Stereoelectronic Properties of Trifluoromethylated Triarylphosphines and the Correlation of their Behaviour as Ligands in the Rh-Catalysed Hydroformylation
Herrera, Daniel,Peral, Daniel,Cordón, Mercedes,Bayón, J. Carles
supporting information, p. 354 - 363 (2020/12/30)
The stereoelectronic properties of a series of trifluoromethylated aromatic phosphines have been studied using different approaches. The σ-donating capability has been evaluated by nuclear magnetic resonance (NMR) spectroscopy of the selenide derivatives and the protonated form of the different trifluoromethylated phosphines. The coupling constants between phosphorous and selenium (1JSeP) and phosphorous and hydrogen (1JHP) can be predicted by empirical equations and correlate the basicity of the phosphines with the number and relative position of trifluoromethyl groups. In contrast, the π-acceptor character of the ligands has been evaluated by measuring the frequency of the CO vibration in the infrared (IR) spectra of the corresponding Vaska type iridium complexes ([IrCl(CO)(PAr3)2], PAr3=triarylphosphine). Moreover, the correlation between the electronic properties and the performance of these phosphines as ligands in the rhodium-catalysed hydroformylation of 1-octene has been established. Phosphines with the lowest basicity, that are those with the highest number of trifluoromethyl groups, gave rise to more active catalytic systems.
Regiocontrolled Reductive Vinylation of Aliphatic 1,3-Dienes with Vinyl Triflates by Nickel Catalysis
Pang, Xiaobo,Zhao, Zhen-Zhen,Wei, Xiao-Xue,Qi, Liangliang,Xu, Guang-Li,Duan, Jicheng,Liu, Xue-Yuan,Shu, Xing-Zhong
supporting information, p. 4536 - 4542 (2021/04/07)
The regiocontrolled functionalization of 1,3-dienes has become a powerful tool for divergent synthesis, yet it remains a long-standing challenge for aliphatic substrates. Herein, we report a reductive approach for a branch-selective 1,2-hydrovinylation of aliphatic 1,3-dienes with R-X electrophiles, which represents a new selectivity pattern for diene functionalization. Simple butadiene, aromatic 1,3-dienes, and highly conjugated polyene were also tolerated. The combination of Ni(0) and the phosphine-nitrile ligand generally resulted in >20:1 regioselectivity with the retention of the geometry of the C3-C4 double bonds. This reaction proceeds with a broad substrate scope, and it allows for the conjugation of two biologically active units to form more complex polyene molecules, such as tetraene and pentaene as well as heptaene.
Stereochemical Alignment in Triphospha[3]ferrocenophanes
Borucki, Stefan,Kelemen, Zsolt,Maurer, Martin,Bruhn, Clemens,Nyulászi, László,Pietschnig, Rudolf
, p. 10438 - 10450 (2017/08/07)
A series of triphospha[3]ferrocenophanes of the type Fe(C5H4-PtBu)2PX with X=H, F, Cl, Br, I, NEt2, tBu has been prepared and characterized by heteronuclear NMR spectroscopy and X-ray crystallography. Despite having three stereogenic centers, the selective formation of a reduced number of diastereomers (either one or two) has been observed for these ferrocenophanes. Theoretical calculations revealed that the inversion of the central stereogenic center inverts the frontier orbital sequence leading to either an iron or a phosphorus centered HOMO depending on the respective diastereomer. CV measurements supported these results. For the all-tert-butyl substituted [3]ferrocenophane Fe(C5H4)2(PtBu)3 a chiral staggered conformation has been found in the solid state which differs substantially from the only other all-organo substituted [3]ferrocenophane, Fe(C5H4)2(PPh)3.
Synthesis of a Tethered myo -Inositol (1,3,4,5,6)Pentakisphosphate (IP5) Derivative as a Probe for Biological Studies
Gregory, Mark,Catimel, Bruno,Yin, Meng-Xin,Condron, Melanie,Burgess, Antony W.,Holmes, Andrew B.
supporting information, p. 121 - 125 (2015/12/26)
There is sufficient evidence to suggest that myo-inositol pentakisphosphate is a vital intermediate species in higher inositol phosphate metabolism, however, its biological roles and physiological function in cells remain uncertain. A tethered myo-inosito
Bis-2-thienyldiethylaminophosphane as a ligand in late transition metal complexes and its transformation to bis-2-thienylphosphane
Granitzka, Markus,Stollberg, Peter,Stalke, Dietmar
, p. 1429 - 1440 (2015/06/16)
Bis-2-thienyldiethylaminophosphane (C4H3S)2PNEt2 (1) is introduced as a ligand for late transition metal complexes ([(H3C4S)2PNEt2]nMXmLp/s
BULK ETHYLENE OLIGOMERIZATION USING A LOW CONCENTRATION OF CHROMIUM CATALYST AND THREE-PART ACTIVATOR
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Page/Page column 19, (2013/03/26)
This invention enables the "bulk" oligomerization of ethylene (i.e. the oligomerization of ethylene in the presence of the oligomer product) using a catalyst system comprising 1) a very low concentration of a chromium catalyst and 2) a three part activato
ETHYLENE OLIGOMERIZATION PROCESS WITH ALIIMINOXANE/ORGANOBORON AS ACTIVATORS USING A HALOGENATED AROMATIC SOLVENT
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Page/Page column 20; 21, (2013/05/23)
This invention provides a two stage process for the oligomerization of ethylene in the presence of a chromium catalyst having a bridging diphosphine ligand. The process mitigates problems which may be experienced during the unsteady state conditions that
HEAT MANAGEMENT IN ETHYLENE OLIGOMERIZATION
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Page/Page column 28-29, (2012/06/16)
The oligomerization of ethylene using a chromium catalyst having a heteroatomic ligand is used to provide oligomerization products that are selective towards hexene and/or octene. However, such processes also typically produce some polymer as an undesired
New water-soluble polyanionic dendrimers - Phosphoric and 1,3,5-benzenetricarboxylic acid derivatives
Salamonczyk, Grzegorz M.
supporting information, p. 10209 - 10217,9 (2020/09/02)
Simple, very efficient, and having some aspects of generality, synthesis of water-soluble, polyanionic dendrimeric polyesters with different size, polarity, and flexibility is described. These macromolecular compounds consisting of phosphate or thiophosph
