Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst.

ABSTRACT: We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels-Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1,2,4,5-tetrazine.

SUBMITTER: Hong L

PROVIDER: S-EPMC5870160 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst.

Hong Longcheng L Ahles Sebastian S Heindl Andreas H AH Tiétcha Gastelle G Petrov Andrey A Lu Zhenpin Z Logemann Christian C Wegner Hermann A HA

Beilstein journal of organic chemistry 20180313

We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels-Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its ...[more]

PMID: 29623123

Similar Datasets

Stable and catalytically active iron porphyrin-based porous organic polymer: Activity as both a redox and Lewis acid catalyst.

Project description:A new porphyrin-based porous organic polymer (POP) with BET surface area ranging from 780 to 880 m(2)/g was synthesized in free-base form via the reaction of meso-tetrakis(pentafluorophenyl) porphyrin and a rigid trigonal building block, hexahydroxytriphenylene. The material was then metallated with Fe(III) imparting activity for Lewis acid catalysis (regioselective methanolysis ring-opening of styrene oxide), oxidative cyclization catalysis (conversion of bis(2-hydroxy-1-naphthyl)methanes to the corresponding spirodienone), and a tandem catalytic processes: an in situ oxidation-cyclic aminal formation-oxidation sequence, which selectively converts benzyl alcohol to 2-phenyl-quinazolin-4(3H)-one. Notably, the catalyst is readily recoverable and reusable, with little loss in catalytic activity.

| S-EPMC4503946 | biostudies-literature

Efficient and Practical Transfer Hydrogenation of Ketones Catalyzed by a Simple Bidentate Mn-NHC Complex.

Project description:Catalytic reductions of carbonyl-containing compounds are highly important for the safe, sustainable, and economical production of alcohols. Herein, we report on the efficient transfer hydrogenation of ketones catalyzed by a highly potent Mn(I)-NHC complex. Mn-NHC 1 is practical at metal concentrations as low as 75 ppm, thus approaching loadings more conventionally reserved for noble metal based systems. With these low Mn concentrations, catalyst deactivation is found to be highly temperature dependent and becomes especially prominent at increased reaction temperature. Ultimately, understanding of deactivation pathways could help close the activity/stability-gap with Ru and Ir catalysts towards the practical implementation of sustainable earth-abundant Mn-complexes.

| S-EPMC6919935 | biostudies-literature

Chemoselective Hydrogenation of Nitroarenes Using an Air-Stable Base-Metal Catalyst.

Project description:The reduction of nitroarenes to anilines as well as azobenzenes to hydrazobenzenes using a single base-metal catalyst is reported. The hydrogenation reactions are performed with an air-and moisture-stable manganese catalyst and proceed under relatively mild reaction conditions. The transformation tolerates a broad range of functional groups, affording aniline derivatives and hydrazobenzenes in high yields. Mechanistic studies suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperative catalysis.

| S-EPMC8041384 | biostudies-literature

Chiral Zn(II)-bisamidine complex as a Lewis-Bronsted combined acid catalyst: application to asymmetric Mukaiyama aldol reactions of ?-ketoesters.

Project description:Focusing on the steric and electronic properties of the resonance-stabilized amidine framework, a cationic metal-bisamidine complex was designed as a conjugated combined Lewis-Brønsted acid catalyst. The chiral Zn(II)-bisamidine catalyst prepared from the 2,2'-bipyridyl derived bisamidine ligand, ZnCl?, and AgSbF? promoted asymmetric Mukaiyama aldol reaction of ?-ketoester and ?,?-disubstituted silyl enol ether to afford the ?-hydroxyester having sequential quarternary carbons in good yield, albeit with low enantioselectivity. Addition of 1.0 equivalent of the fluoroalcohol having suitable acidity and bulkiness dramatically increased the enantioselectivity (up to 68% ee). DFT calculations suggested that this additive effect would be caused by self-assembly of the fluoroalcohol on the Zn(II)-bisamidine catalyst.

| S-EPMC6268631 | biostudies-literature

A robust, air-stable, reusable ruthenium catalyst for dehydrogenation of ammonia borane.

Project description:We describe an efficient homogeneous ruthenium catalyst for the dehydrogenation of ammonia borane (AB). This catalyst liberates more than 2 equiv of H(2) and up to 4.6 system wt % H(2) from concentrated AB suspensions under air. Importantly, this catalyst is robust, delivering several cycles of dehydrogenation at high [AB] without loss of catalytic activity, even with exposure to air and water.

| S-EPMC3168700 | biostudies-literature

Lewis versus Bronsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation.

Project description:Lewis acid (LA) activation by coordination to metal oxido species has emerged as a new strategy in catalytic oxidations. Despite the many reports of enhancement of performance in oxidation catalysis, direct evidence for LA-catalyst interactions under catalytically relevant conditions is lacking. Here, we show, using the oxidation of alkenes with H2O2 and the catalyst [Mn2(μ-O)3(tmtacn)2](PF6)2 (1), that Lewis acids commonly used to enhance catalytic activity, e.g., Sc(OTf)3, in fact undergo hydrolysis with adventitious water to release a strong Brønsted acid. The formation of Brønsted acids in situ is demonstrated using a combination of resonance Raman, UV/vis absorption spectroscopy, cyclic voltammetry, isotope labeling, and DFT calculations. The involvement of Brønsted acids in LA enhanced systems shown here holds implications for the conclusions reached in regard to the relevance of direct LA-metal oxido interactions under catalytic conditions.

| S-EPMC6832668 | biostudies-literature

Catalytic Synthesis of Oligosiloxanes Mediated by an Air Stable Catalyst, (C6F5)3B(OH2).

Project description:The utility of (C6F5)3B(OH2) as catalyst for the simple and environmentally benign synthesis of oligosiloxanes directly from hydrosilanes, is reported. This protocol offers several advantages compared to other methods of synthesizing siloxanes, such as mild reaction conditions, low catalyst loading, and a short reaction time with high yields and purity. The considerable H2O-tolerance of (C6F5)3B(OH2) promoted a catalytic route to disiloxanes which showed >99% conversion of three tertiary silanes, Et3SiH, PhMe2SiH, and Ph3SiH. Preliminary data on the synthesis of unsymmetrical disiloxanes (Si-O-Si') suggests that by modifying the reaction conditions and/or using a 1:1 combination of silane to silanol the cross-product can be favored. Intramolecular reactions of disilyl compounds with catalytic (C6F5)3B(OH2) led to the formation of novel bridged siloxanes, containing a Si-O-Si linkage within a cyclic structure, as the major product. Moreover, the reaction conditions enabled recovery and recycling of the catalyst. The catalyst was re-used 5 times and demonstrated excellent conversion for each substrate at 1.0 mol% catalyst loading. This seemingly simple reaction has a rather complicated mechanism. With the hydrosilane (R3SiH) as the sole starting material, the fate of the reaction largely depends on the creation of silanol (R3SiOH) from R3SiH as these two undergo dehydrocoupling to yield a disiloxane product. Generation of the silanol is based on a modified Piers-Rubinsztajn reaction. Once the silanol has been produced, the mechanism involves a series of competitive reactions with multiple catalytically relevant species involving water, silane, and silanol interacting with the Lewis acid and the favored reaction cycle depends on the concentration of various species in solution.

| S-EPMC7325218 | biostudies-literature

A practical and catalyst-free trifluoroethylation reaction of amines using trifluoroacetic acid.

Project description:Amines are a fundamentally important class of biologically active compounds and the ability to manipulate their physicochemical properties through the introduction of fluorine is of paramount importance in medicinal chemistry. Current synthesis methods for the construction of fluorinated amines rely on air and moisture sensitive reagents that require special handling or harsh reductants that limit functionality. Here we report practical, catalyst-free, reductive trifluoroethylation reactions of free amines exhibiting remarkable functional group tolerance. The reactions proceed in conventional glassware without rigorous exclusion of either moisture or oxygen, and use trifluoroacetic acid as a stable and inexpensive fluorine source. The new methods provide access to a wide range of medicinally relevant functionalized tertiary ?-fluoroalkylamine cores, either through direct trifluoroethylation of secondary amines or via a three-component coupling of primary amines, aldehydes and trifluoroacetic acid. A reduction of in situ-generated silyl ester species is proposed to account for the reductive selectivity observed.

| S-EPMC5490195 | biostudies-literature

Ni-citric acid coordination polymer as a practical catalyst for multicomponent reactions.

Project description:Coordinative polymers (CP) are a subclass of Metal-organic frameworks (MOFs) with porous microstructures which have been widely synthesized in recent years and applied in various fields especially in catalysis science. In this work Coordinative polymers (CP) of nickel and citric acid (CA) was prepared as a new catalyst (Ni-CP) and applied in organic multicomponent reactions. The obtained catalyst was characterized by SEM, WDX, EDS, AAS, FT-IR, XRD and BET analysis. N2 adsorption-desorption isotherms indicate good BET surface area for Ni-CP; therefore can be employed as an efficient catalyst in multicomponent reactions for the synthesis of polyhydroquinoline and 2,3-dihydroquinazolin-4(1H)-one derivatives. Finally, this catalyst was recovered and reused several consecutive times.

| S-EPMC8714820 | biostudies-literature

"Activated Borane": A Porous Borane Cluster Polymer as an Efficient Lewis Acid-Based Catalyst.

Project description:Borane cluster-based porous covalent networks, named activated borane (ActB), were prepared by cothermolysis of decaborane(14) (nido-B10H14) and selected hydrocarbons (toluene, ActB-Tol; cyclohexane, ActB-cyHx; and n-hexane, ActB-nHx) under anaerobic conditions. These amorphous solid powders exhibit different textural and Lewis acid (LA) properties that vary depending on the nature of the constituent organic linker. For ActB-Tol, its LA strength even approaches that of the commonly used molecular LA, B(C6F5)3. Most notably, ActBs can act as heterogeneous LA catalysts in hydrosilylation/deoxygenation reactions with various carbonyl substrates as well as in the gas-phase dehydration of ethanol. These studies reveal the potential of ActBs in catalytic applications, showing (a) the possibility for tuning catalytic reaction outcomes (selectivity) in hydrosilylation/deoxygenation reactions by changing the material's composition and (b) the very high activity toward ethanol dehydration that exceeds the commonly used γ-Al2O3 by achieving a stable conversion of ∼93% with a selectivity for ethylene production of ∼78% during a 17 h continuous period on stream at 240 °C.

| S-EPMC10660343 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data