160298-76-0Relevant academic research and scientific papers
In vitro biological, catalytic, and DFT studies of some iron(III) N-ligated complexes
Hijazi, Ahmed K.,Taha, Ziyad A.,Ababneh, Taher S.,Alshare, Heba M.,Al-Bataineh, Nezar,Al-Momani, Waleed M.,Ajlouni, Abdulaziz M.
, p. 1561 - 1572 (2020)
Fe(III) complexes, [Fe(CH3CN)6][X]3 and [Fe(CH3CH2CN)6][X]3 (where X: counter anion = B{C6H3(m-CF3)2}4)? and B(C
Ammonium Complexes of Orthoester Cryptands Are Inherently Dynamic and Adaptive
Wang, Xiang,Shyshov, Oleksandr,Han?eva?ki, Marko,J?ger, Christof M.,Von Delius, Max
, p. 8868 - 8876 (2019)
Fluxional chemical species such as bullvalene have been a valuable source of inspiration and fundamental insight into the nature of chemical bonds. A supramolecular analogue of bullvalene, i.e., a "fluxional host-guest system", in which the ensemble of a well-defined host and guest is engaged in continuous, degenerate constitutional rearrangements, is still elusive, however. Here, we report experimental and computational evidence for guest-induced dynamic covalent rearrangements in the ammonium complexes of self-assembled orthoester cryptands. This unique behavior is made possible by the ammonium guest playing a dual role: it is sufficiently acidic to initiate dynamic covalent exchange reactions at the orthoester bridgeheads, and as a hydrogen bond donor it acts as a supramolecular template, governing the outcome of a multitude of possible intra- and intermolecular rearrangement reactions. One particularly striking example of inherent dynamic behavior was observed in host-guest complex [NH4+o-Me2-2.1.1], which spontaneously rearranged into the larger and thermodynamically more stable complex [NH4+o-Me2-2.2.1], even though this process led to the formation of poor host o-Me2-1.1.1 as a consequence of the excess of one subcomponent (diethylene glycol; "1" in our nomenclature). These inherently adaptive host-guest networks represent a unique platform for exploring the interrelationship between kinetic and thermodynamic stability. For instance, as a result of optimal NH4+ binding, complex [NH4+o-Me2-2.2.1] was found to be thermodynamically stable (negligible intermolecular rearrangements over weeks), whereas computational studies indicate that the compound is far from kinetically stable (intramolecular rearrangements).
Redox-switchable ring-opening polymerization by tridentate ONN-type titanium and zirconium catalysts
Burroughs, Justin M.,Doerr, Alicia M.,Legaux, Nicholas M.,Long, Brian K.
, p. 6501 - 6510 (2020)
The field of redox-switchable catalysis has gained considerable interest in recent years, enabling catalytic activity and/or selectivity to be oscillated based upon the oxidation-state of the ligand and/or active metal center. Unfortunately, though myriad redox-switchable catalysts have been developed for the ring-opening polymerization of cyclic esters, further fundamental structure-catalytic performance studies are needed to better ascertain how systematic changes in ligand structure impact catalytic activity and redox-switchability. Herein, we describe our studies designed to determine how the number of ligand-based redox_active moieties impacts catalytic performance. More specifically, we compare symmetric catalysts bearing tetradentate [ONNO] ligands with two redox_active moieties to related asymmetric catalysts bearing tridentate [ONN] ligands featuring only a single redox_active moiety. The results of these studies reveal that the number of redox_active moieties may not play a crucial role in the catalysts' switchability; however, the choice of metal center may dramatically influence catalyst activity, stability, and redox-switchability. This journal is
Hydrogen-Bonding-Assisted Exogenous Nucleophilic Reagent Effect for β-Selective Glycosylation of Rare 3-Amino Sugars
Zeng, Jing,Wang, Ruobin,Zhang, Shuxin,Fang, Jing,Liu, Shanshan,Sun, Guangfei,Xu, Bingbing,Xiao, Ying,Fu, Dengxian,Zhang, Wenqi,Hu, Yixin,Wan, Qian
supporting information, p. 8509 - 8515 (2019/06/13)
Challenges for stereoselective glycosylation of deoxy sugars are notorious in carbohydrate chemistry. We herein report a novel strategy for the construction of the less investigated β-glycosidic bonds of 3,5-trans-3-amino-2,3,6-trideoxy sugars (3,5-trans-3-ADSs), which constitute the core structure of several biologically important antibiotics. Current protocol leverages a C-3 axial sulfonamide group in 3,5-trans-3-ADSs as a hydrogen-bond (H-bond) donor and repurposes substoichiometric phosphine oxide as an exogenous nucleophilic reagent (exNu) to establish an intramolecular H-bond between the former and the derived α-oxyphosphonium ion. This pivotal interaction stabilizes the α-face-covered intermediate to inhibit the formation of the more reactive β-intermediate, thereby yielding reversed β-selectivity, which is unconventional for an exNu-mediated glycosylation system. A wide range of substrates was accommodated, and good to excellent β-selectivities were ensured by this H-bonding-assisted exNu effect. The robustness of the current strategy was further attested by the architectural modification of natural products and drugs containing 3,5-trans-3-ADSs, as well as the synthesis of a trisaccharide unit in avidinorubicin.
Method for catalytic synthesis of binaphtholamine by chiral phosphate
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Paragraph 0088; 0091, (2019/04/10)
The invention belongs to the field of asymmetric synthesis, and discloses a method for catalytic synthesis of binaphtholamine by chiral phosphate. The method comprises the following steps: with chiralphosphoric acid or chiral phosphate as a catalyst, allo
Adaptive Behavior of Dynamic Orthoester Cryptands
Shyshov, Oleksandr,Brachvogel, René-Chris,Bachmann, Tobias,Srikantharajah, Rubitha,Segets, Doris,Hampel, Frank,Puchta, Ralph,von Delius, Max
supporting information, p. 776 - 781 (2017/01/14)
The integration of dynamic covalent bonds into macrocycles has been a tremendously successful strategy for investigating noncovalent interactions and identifying effective host–guest pairs. While numerous studies have focused on the dynamic responses of macrocycles and larger cages to various guests, the corresponding constitutionally dynamic chemistry of cryptands remains unexplored. Reported here is that cryptands based on orthoester bridgeheads offer an elegant entry to experiments in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents. In such dynamic mixtures, the alkali metal ions Li+, Na+, K+, Rb+, and Cs+exhibit pronounced preferences for the formation of cryptands of certain sizes and donor numbers, and the selection is rationalized by DFT calculations. Reported is also the first self-assembly of a chiral orthoester cryptate and a preliminary study on the use of stereoisomers as subcomponents.
Organonitrile ligated silver complexes with perfluorinated weakly coordinating anions and their catalytic application for coupling reactions
Zhang, Yanmei,Santos, Ana M.,Herdtweck, Eberhardt,Mink, Janos,Kuehn, Fritz E.
, p. 366 - 370 (2007/10/03)
Homogeneous catalytic processes mediated by silver(I) complexes are relatively rare. This work describes the synthesis and characterization of acetonitrile ligated silver salts with three weakly coordinating anions [B(C6F5)4]- [B{C6H 3(CF3)2}4]- and [(C 6F5)3B-C3H4N 2-B(C6F5)3]-. The silver cation is coordinated either by four or by two acetonitrile ligands. All examined Ag(I) complexes show catalytic activity in coupling reactions of terminal alkynes with aldehydes and amines. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
Kinetics and mechanisms of methyl vinyl ketone hydroalkoxylation catalyzed by palladium(II) complexes
Miller, Kimberly J.,Kitagawa, Terutaka T.,Abu-Omar, Mahdi M.
, p. 4403 - 4412 (2008/10/08)
Palladium(II) coordination complexes such as (CH3CN)2PdCl2, 1, catalyze the addition of alcohols to vinyl ketones to produce ethers. During the catalytic cycle, the alcohol adds selectively to the β-carbon (anti-Markovnikov). The kinetics for the reaction of benzyl alcohol (BA) with methyl vinyl ketone (MVK) as catalyzed by 1 has been investigated in detail. The experimental rate law is first-order in catalyst and BA and features saturatiost and BA and features saturatioonitrile is a competitive inhibitor for MVK. The most consistent mechanism with the experimental findings involves substitution of an acetonitrile ligand by MVK in a preequilibrium step (K1 = 0.020 ± 0.004 in CDCl3 at 25°C) followed by nucleophilic attack of benzyl alcohol (k2 = (7.6 ± 0.8) × 10-3 M-1 s-1 in CDCl3 at 25°C). A kinetic isotope effect has been noted for the reaction in the limit of saturated MVK (k2H/k2D = 2.0). MVK coordinates to palladium affording an η2-alkene adduct. The rate constants for several alcohols are reported; the catalytic reaction is sensitive to steric hindrance of the alcohol nucleophile: 1° > 2° ? 3°. Appreciable kinetic effects are observed by variation of the substituents on BA. Two new palladium(II) coordination complexes containing bidentate and tridentate pyridyl imine ligands have been synthesized, fully characterized, and explored as catalysts for the hydroalkoxylation reaction. The synthesis of AgBAr4F and its use in metathesis reactions with Pd(II) complexes are described. A mechanism has been put forth where the carbonyl group of the olefin interacts with palladium and directs the alcohol addition to the β-carbon, resulting in the anti-Markovnikov addition ether product. Finally, the charge of the palladium complex augments catalytic activity.
