10437-78-2Relevant articles and documents
An air oxidizable bimetallic palladium(II) catalyst for asymmetric allylic oxidation of olefins in acetic acid
El-Qisiari, Arab K.,Qaseer, Hanan A.,Henry, Patrick M.
, p. 4229 - 4231 (2002)
A bimetallic palladium(II) complex containing a triketone ligand and a bridging diphosphine ligand oxidizes olefins in acetic acid to allylic acetates by a direct air oxidation, which does not require intermediate redox systems. When the diphosphine is chiral, an asymmetric reaction occurs which gives enantioselectivities between 52 and 78% for cyclic olefins.
A novel approach for the formation of carbon-nitrogen bonds: Azidation of alkyl radicals with sulfonyl azides
Ollivier,Renaud
, p. 4717 - 4727 (2001)
Two preparatively attractive methods for the azidation of alkyl radicals are described. Secondary and tertiary alkyl iodides and dithiocarbonates are easily converted into the corresponding azides, either by reaction with ethanesulfonyl azide in the prese
The effects of the solvent and the ligand chirality on the regioselectivity of alkene oxidative esterification by PdII carboxylates
Kozitsyna,Martens,Stolyarov,Gekhman,Vargaftik,Moiseev
, p. 1673 - 1681 (1999)
The effects of the solvent and the ligand chirality on the regioselectivity of oxidative esterificanon of propylene and cyclohexene by PdII carboxylates were studied using achiral (MeCO2-, Me2CHCH2CO2-), racemic ((±)-CF3CF2CF2OC*F(CF3) CO2-) and chiral ((S)-(+)-MeC*H(Et)CO2-, (+)-CF3CF2CF2OC*F(CF3)CO2 -) carboxylate ligands. The oxidation of alkenes in aprotic media (CHCl3, CH2C12, CO2, THF) affords mainly allylic esters (in the case of cyclohexene also homoallylic esters) and the oxidative esterification at the vinylic position is absent. In weakly solvating media (CHCl3, CH2Cl2) the regioselectivity of cyclohexene oxidation (the allyl to homoallyl ratio) increases substantially on going from achiral or racemic acido ligands to chiral acido ligands. In a more donor medium (THF) the ligand chirality effect almost vanishes. The effects of the ligand chirality and the nature of the solvent on the mechanism of alkene oxidation by PdII complexes are discussed.
Palladium-catalyzed allylic acetoxylation: an exploratory study of the influence of added acids
Akermark, Bjoern,Hansson, Sverker,Rein, Tobias,Vagberg, Jan,Heumann, Andreas,Baeckvall, Jan-Erling
, p. 433 - 444 (1989)
In order to investigate the possibility of improving the selectivity in palladium-catalyzed acetoxylation of substituted cycloalkenes and linear alkenes, the influence of added strong acids has been studied.It was found that the product selectivity can be increased in some cases, but also that side reactions lower the total yields when trifluoroacetic or stronger acids are used.The improvement of the selectivity may possibly be due to a change in mechanism for the acetoxylation.
Photoredox/Cobalt Dual-Catalyzed Decarboxylative Elimination of Carboxylic Acids: Development and Mechanistic Insight
Cartwright, Kaitie C.,Joseph, Ebbin,Comadoll, Chelsea G.,Tunge, Jon A.
, p. 12454 - 12471 (2020/09/09)
Recently, dual-catalytic strategies towards the decarboxylative elimination of carboxylic acids have gained attention. Our lab previously reported a photoredox/cobaloxime dual catalytic method that allows the synthesis of enamides and enecarbamates directly from N-acyl amino acids and avoids the use of any stoichiometric reagents. Further development, detailed herein, has improved upon this transformation's utility and further experimentation has provided new insights into the reaction mechanism. These new developments and insights are anticipated to aid in the expansion of photoredox/cobalt dual-catalytic systems.
Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins
Lin, Bo-Lin,Labinger, Jay A.,Bercaw, John E.
experimental part, p. 264 - 271 (2009/10/23)
Several pyridine-like ligands were found to improve Pd(OAc) 2-catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid. The best ligand examined, bipyrimidine, was used to identify the catalyst precursor for this system, (bipyrimidine)Pd(OAc) 2, which was fully characterized. Mechanistic studies suggest the reaction takes place through disproportionation of (bipyrimidine)Pd(OAc) 2 to form a bipyrimidine-bridged dimer, which reacts with olefin to form a PdII-olefin adduct, followed by allylic C-H activation to produce (η3-allyl)PdII species. The (η3-allyl)PdII intermediate undergoes a reversible acetate attack to generate a Pd0-(allyl acetate) adduct, which subsequently reacts with p-benzoquinone to release allyl acetate and regenerate (bipyrimidine)Pd(OAc)2. No KIE is observed for the competition experiment between allylbenzene-d0 and allylbenzene-d5 (CD2=CDCD2C6H5), suggesting that allylic C-H activation is not rate-determining. Catalytic allylic acetoxylations of other terminal olefins as well as cyclohexene were also effected by (bipyrimidine)Pd(OAc)2.
Vinylic, allylic and homoallylic oxidations of alkenes via π- and σ-organopalladium complexes
Kozitsyna, N.Yu.,Vargaftik,Moiseev
, p. 274 - 291 (2007/10/03)
The stoichiometric and catalytic pathways of oxidative esterification of alkenes via intermediate organopalladium complexes are discussed. The oxidation of propylene, hex-1-ene and cyclohexene by PdII acido complexes containing achiral, racemic and chiral carboxylate ligands was first studied in a series of solvents other than acetic acid. Significant changes in the selectivity of the PdII-promoted reaction with changes in the solvent nature and ligand chirality were observed. A way to allylic esters based on low-valence Pd nanoclusters provide highly selective oxidation of acyclic alkenes into allylic esters, whereas cycloalkenes undergo mostly redox disproportionation. The role of π-alkene, σ-alkenyl and π-allyl complexes in the mechanism of the alkene oxidative esterification with PdII complexes and low-valence Pd clusters is discussed.
Aziridination of Cyclohex-3-en-1-ol
Atkinson, Robert S.,Kelly, Brian J.,McNicolas, Carole
, p. 562 - 564 (2007/10/02)
In contrast to peracid epoxidation of the title homoallylic alcohol, aziridination using acetoxyaminoquinazolone (1) is stereospecific.
Factors Influencing Conformational Preferences in Cyclohexenes
Lambert, Joseph B.,Marko, Dale E.
, p. 7978 - 7982 (2007/10/02)
Conformational preferences have been measured for the first time for 4-substituted cyclohexenes in a solvent of low polarity.Measurements were made for the substituents Cl, Br, I, OH, OSiMe3, and CN and were compared with conformational preferences in cyclohexyl and exo-methylenecyclohex-3-yl.In the nearly nonpolar solvent CF2Cl2, in which intramolecular interactions are maximized, there is a much larger axial population for cyclohexen-4-yl than in cyclohexyl or exo-methylenecyclohex-3-yl.In particular, the dipolar interaction of the endocyclic double bond is reduced from that of the exocyclic double bond.This observation is confirmed by the almost negligible effect of symmetrizing the endocyclic double bond through 1,2-dimethyl substitution, in contrast with the large effect of symmetrizing the exocyclic double bond through 7,7-dimethyl substitution.Polar solvents increase the proportion of the axial conformer to a smaller extent for the endocyclic than for the exocyclic system, again in agreement with a lower dipolar effect in the endocyclic case.These results emphasize the anisotropic nature of the steric effects of double bonds.
Metal Ion Oxidation. VIII. Oxidation of Organic Compounds by Copper(III)
Joensson, Lennart
, p. 683 - 690 (2007/10/02)
The copper(III) complex of biuret has been shown to oxidize aromatic and alicyclic compounds in acetic and trifluoroacetic acid, yielding acetates and dehydro dimers.The product pattern of these reactions supports an electron transfer mechanism.Aryl halides, e.g. fluorobenzene, are hydrolyzed to phenols and the mechanism is postulated to be an electron transfer chain mechanism, the SON2 mechanism.Substituted arylacetic acids are decarboxylated when treated with 1 in acetic acid at reflux temperature.This decarboxylation is proposed to be a one-electron process, the rate-determining step being the decomposition of an arylacetic acid-copper(III) complex to a benzylic radical.
