5452-75-5Relevant academic research and scientific papers
Dramatic tuning of ligand donor properties in (Ttz)CuCO through remote binding of H+ (Ttz = hydrotris(triazolyl)borate)
Dixon, Natalie A.,McQuarters, Ashley B.,Kraus, Jodi S.,Soffer, Jonathan B.,Lehnert, Nicolai,Schweitzer-Stenner, Reinhard,Papish, Elizabeth T.
, p. 5571 - 5573 (2013)
Complexes with bulky hydrotris(triazolyl)borate (Ttz) ligands, TtzCuCO, were used to probe how acids change the donor properties of Ttz ligands. (TtztBu,Me)CuCO shows four distinct protonation states and a gradual increase in the CO stretch. The increased electrophilic nature of the Cu center upon protonation leads to enhanced C-H activation catalysis.
Highly regioselective functionalization of aliphatic carbon-hydrogen bonds with a perbromohomoscorpionate copper(I) catalyst
Caballero, Ana,Diaz-Requejo, M. Mar,Belderrain, Tomas R.,Nicasio, M. Carmen,Trofimenko, Swiatoslaw,Perez, Pedro J.
, p. 1446 - 1447 (2003)
The complex TpBr3Cu(NCMe) (1) is an excellent catalyst for the regioselective carbene transfer reaction to tertiary C-H bonds of hydrocarbons, at room temperature, using the readily available ethyl diazoacetate (EDA) as the carbene source. Copyright
Alkoxydiaminophosphine Ligands as Surrogates of NHCs in Copper Catalysis
Pizarro, Juan Diego,Molina, Francisco,Fructos, Manuel R.,Pérez, Pedro J.
supporting information, p. 10330 - 10335 (2020/07/24)
A family of phosphine ligands containing a five-membered ring similar to the popular N-heterocyclic carbene ligands and an alkoxy third substituent has been developed. These alkoxydiaminophosphine ligands (ADAP) can be generated in one pot and reacted with a copper(I) source leading to the high yield isolation of complexes [(ADAP)CuX]2 (X=Cl, Br). The dinuclear nature of these compounds has been established by means of X-ray studies and DOSY experiments. A screening of the catalytic properties of these complexes toward carbene-transfer reactions from diazocompounds to C?H bonds (alkane, arene), olefins or N?H bonds, as well as in CuAAC or nitrene transfer reactions have shown a performance at least similar, if not better, than their (NHC)CuCl analogues, opening a new window in copper catalysis with these readily tunable ADAP ligands.
Iron-Catalyzed Intermolecular Functionalization of Non-Activated Aliphatic C?H Bonds via Carbene Transfer
Rodríguez, Mònica,Font, Gemma,Nadal-Moradell, Joel,Hernán-Gómez, Alberto,Costas, Miquel
supporting information, p. 5116 - 5123 (2020/10/06)
The modification of strong Csp3?H bonds via iron carbene intermediates under mild reaction conditions has been an important challenge with attractive prospective in organic synthesis. In this work, we show the efficient combination of an electrophilic iron catalyst with a lithium Lewis acid for the functionalization of strong Csp3?H bonds of cyclic and linear alkanes by the activation of commercially available ethyl diazoacetate (EDA). The reaction proceeds with good yields, under mild reaction conditions (40 °C) and large excess of substrate is not needed. In addition, excellent activity is observed in the cyclopropanation of challenging aliphatic olefins. (Figure presented.).
Selective hydrogenation of α,β-unsaturated carbonyl compounds on silica-supported copper nanoparticles
Mendes-Burak, Jorge,Ghaffari, Behnaz,Copéret, Christophe
supporting information, p. 179 - 181 (2019/01/04)
Silica-supported copper nanoparticles prepared via surface organometallic chemistry are highly efficient for the selective hydrogenation of various α,β-unsaturated carbonyl compounds yielding the corresponding saturated esters, ketones, and aldehydes in the absence of additives. High conversions and selectivities (>99%) are obtained for most substrates upon hydrogenation at 100-150 °C and under 25 bar of H2.
Improving Catalyst Activity in Hydrocarbon Functionalization by Remote Pyrene–Graphene Stacking
Ballestin, Pilar,Ventura-Espinosa, David,Martín, Santiago,Caballero, Ana,Mata, Jose A.,Pérez, Pedro J.
, p. 9534 - 9539 (2019/06/04)
A copper complex bearing an N-heterocyclic carbene ligand with a pyrene “tail” attached to the backbone has been prepared and supported on reduced graphene oxide (rGO). The free and supported copper materials have been employed as homogeneous and heterogeneous catalysts in the functionalization of hydrocarbons such as n-hexane, cyclohexane, and benzene through incorporation of the CHCO2Et unit from ethyl diazoacetate. The graphene-anchored complex displays higher reaction rates and induces higher yields than its soluble counterpart, features that can be rationalized in terms of a decrease in electron density at the metal center due to a remote net electronic flux from the supported copper complex to the graphene surface.
Blue light-promoted photolysis of aryldiazoacetates
Jurberg, Igor D.,Davies, Huw M. L.
, p. 5112 - 5118 (2018/06/12)
Aryldiazoacetates can undergo photolysis under blue light irradiation (460-490 nm) at room temperature and under air in the presence of numerous trapping agents, such as styrene, carboxylic acids, amines, alkanes and arenes, thus providing a straighforward and general platform for their mild functionalization.
Enhanced Electrophilicity of Heterobimetallic Bi-Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study
Collins, Lee R.,Van Gastel, Maurice,Neese, Frank,Fürstner, Alois
supporting information, p. 13042 - 13055 (2018/10/15)
Dirhodium paddlewheel complexes are indispensable tools in modern organometallic catalysis for the controlled decomposition of diazo-compounds. Tuning the reactivity of the thus-formed transient carbenes remains an active and dynamic field of research. Herein, we present our findings that the distal metal center plays an as yet underappreciated role in modulating this reactivity. Replacement of one rhodium atom in the bimetallic core for bismuth results in the formation of a significantly more electrophilic carbene complex. Bismuth-rhodium catalysts thereby facilitate previously unknown modes of reactivity for α-diazoester compounds, including the cyclopropanation of alkenes as electron deficient as trichloroethylene. While dirhodium paddlewheel complexes remain the catalysts of choice for many carbene-mediated transformations, their bismuth-rhodium analogues exhibit complementary reactivity and show great potential for small molecule and solvent activation chemistry. DFT calculations highlight the importance of metal-metal bonding interactions in controlling carbene electrophilicity. The paucity of these interactions between the 4d orbitals of rhodium and the 6p orbitals of bismuth results in weaker π-back-bonding interactions for bismuth-rhodium carbene complexes compared to dirhodium carbene complexes. This leads to weakening of the rhodium-carbene bond and to a more carbene-centered LUMO, accounting for the observed enhancement in bismuth-rhodium carbene electrophilicity. These findings are supported by a detailed spectroscopic study of the "donor-donor" carbene complexes Rh2(esp)2C(p-MeOPh)2 (19) and BiRh(esp)2C(p-MeOPh)2 (20), employing a combination of UV-vis and resonance Raman spectroscopy. The results reveal that carbene chemoselectivity in MRh(L)4 catalysis can be modulated to a previously unrecognized extent by the distal metalloligand.
Water as the Reaction Medium for Intermolecular C-H Alkane Functionalization in Micellar Catalysis
álvarez, María,Gava, Riccardo,Rodríguez, Manuel R.,Rull, Silvia G.,Pérez, Pedro J.
, p. 3707 - 3711 (2017/06/09)
A series of alkanes CnH2n+2 have been functionalized in water as the reaction medium, using a silver-based catalyst, upon the insertion of carbene (CHCO2Et from N2CHCO2Et) groups into the carbon-hydrogen bonds of hexane, cyclohexane, or 2-methylbutane, among others. The regioselectivity toward the distinct reaction sites is identical to that found in neat alkane, the water-based system allowing the use of a much shorter excess of the hydrocarbon. This is the first example of the intermolecular functionalization of alkanes with this strategy in water. The functionalized alkanes partially undergo the incorporation of a second carbene unit to provide α-(acyloxy)acetates, in an unprecedented tandem reaction of this nature.
CATALYST AND BATTERY COMPONENTS DERIVED FROM CONDENSATION REACTIONS WITH CARBA-CLOSO-DODECABORATE AMINES
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Paragraph 0278, (2015/10/05)
Described herein is the fusion of two families of unique carbon-containing molecules that readily disregard the tendency of carbon to form four chemical bonds, namely N-heterocyclic carbenes (NHCs) and carborane anions. Deprotonation of an anionic imidazolium salt with lithium diisopropylamide at room temperature leads to a mixture of lithium complexes of C-2 and C-5 dianionic NHC constitutional isomers as well as a trianionic (C-2, C-5) adduct. Judicious choice of the base and reaction conditions allows for the selective formation of all three stable polyanionic carbenes. In solution, the so-called abnormal C-5 NHC lithium complex slowly isomerizes to the normal C-2 NHC, and the process can be proton catalyzed by the addition of the anionic imidazolium salt. These results indicate that the combination of two unusual forms of carbon atoms can lead to unexpected chemical behavior, and that this strategy paves the way for the development of a broad new generation of NHC ligands for catalysis.
