1896-62-4Relevant academic research and scientific papers
Stereospecific alkyne reduction: Novel activity of old yellow enzymes
Mueller, Andre,Stuermer, Rainer,Hauer, Bernhard,Rosche, Bettina
, p. 3316 - 3318 (2007)
Old enzyme, new trick: An environmentally sustainable alternative for the regio-and stereoselective reduction of the alkyne bond is the biotransformation by "Old Yellow Enzyme" (OYE). This "old" enzyme, first isolated in 1932, catalyzes the trans-selective hydrogenation of the carbon-carbon triple bond under mild conditions. (Chemical Equation Presented).
Nanosized metallic particles embedded in silica and carbon aerogels as catalysts in the Mizoroki-Heck coupling reaction
Martínez, Sandra,Vallribera, Adelina,Cotet, Cosmin L.,Popovici, Mihaela,Martín, Laura,Roig, Anna,Moreno-Ma?as, Marcial,Molins, Elies
, p. 1342 - 1345 (2005)
We have prepared silica, organic, and carbon aerogels doped with metallic Ni and Pd through sol-gel processes. Silica aerogel nanocomposites have been synthesized by impregnation, with Ni(acac)2 or Pd(acac)2, of the silica wet gels followed by ethanol supercritical drying. Organic aerogels were prepared by sol-gel copolymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion exchange with either Ni(NO3)2 · 6H2O or Pd(OAc) 2 and CO2 supercritical drying. No special reduction step was needed. Organic aerogels were further carbonized to obtain carbon aerogels. Pd organic and carbon aerogels containing 20-40% palladium nanoparticles are good catalysts for the Mizoroki-Heck reaction. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
Tuning the hydrogen donor/acceptor behavior of ionic liquids in Pd-catalyzed multi-step reactions
López-Vinasco, Angela M.,Guerrero-Ríos, Itzel,Favier, Isabelle,Pradel, Christian,Teuma, Emmanuelle,Gómez, Montserrat,Martin, Erika
, p. 56 - 61 (2015)
Palladium nanoparticles stabilized by thioether-phosphine ligands (1-3) were used as catalytic precursors in Heck-Mizoroki cross-coupling and CC reduction reactions in ionic liquids. The ionic liquid [EMI][MeHPO3] (A) exhibited an important hydrogen donor/acceptor behavior depending on the reaction conditions. Tandem or parallel pathways for C-C coupling and H-transfer reactions were observed, leading to the coupled product trans-4-phenyl-3-buten-2-one (I) and the corresponding reduced partner 4-phenylbutan-2-one (II) pointing to a molecular-like catalytic reactivity of the process. When the reaction was carried out under hydrogen pressure and low temperature, the reduction to II was inhibited by the presence of thioether-phosphine ligands.
Z- and E-selective Horner–Wadsworth–Emmons reactions
Molnár, Katalin,Takács, László,Kádár, Mihály,Faigl, Ferenc,Kardos, Zsuzsanna
, p. 1214 - 1224 (2017)
In the present work, we determined and evaluated the stereochemical outcome of the Horner–Wadsworth–Emmons (HWE) reaction of 2-oxoalkylphosphonates with different ester functions (bis(2,2,2-trifluoroethyl), 2,2,2-trifluoroethyl methyl, dimethyl) and side chains (aliphatic, aromatic) with three different aldehydes (benzaldehyde, THP- and PPB-protected Corey aldehydes) under two reaction conditions. The “trans” protocol is generally used in the E-selective HWE reactions, while “cis” protocol promotes the Z-selectivity.
Metal-Controlled Selective [3+2] Cyclization Reactions of Alkenyl Fischer Carbene Complexes and Allenes
Barluenga, Jose,Vicente, Ruben,Barrio, Pablo,Lopez, Luis A.,Tomas, Miguel
, p. 5974 - 5975 (2004)
Chromium alkenyl Fischer carbene complexes undergo selective [3+2] cyclization reactions to allenes in the presence of nickel(0) or rhodium(I) catalysts. Interestingly, the chemo- and regioselectivity of the process are entirely dependent on the nature of the metal. Copyright
Iron-catalyzed oppenauer-type oxidation of alcohols
Coleman, Michael G.,Brown, Alec N.,Bolton, Brett A.,Guan, Hairong
, p. 967 - 970 (2010)
A (hydroxycyclopentadienyl)iron dicarbonyl hydride catalyzes the Oppenauer-type oxidation of alcohols with acetone as the hydrogen acceptor. Many functional groups are tolerant to the oxidation conditions. The same complex also catalyzes the dehydrogenation of diols to lactones. A mechanism involving the formation of iron-alcohol complexes and their rapid ligand exchange with free alcohols is proposed. The trimethylsilyl groups on the cyclopentadienyl ligand of the catalyst play a critical role in stabilizing the iron hydride and increasing the catalyst lifetime.
Metalloporphyrin-catalyzed diastereoselective epoxidation of allyl-substituted alkenes
Chan, Wing-Kei,Wong, Man-Kin,Che, Chi-Ming
, p. 4226 - 4232 (2005)
By using [Mn(2,6-Cl2TPP)Cl] (1) as a catalyst and Oxone/H 2O2 as an oxidant, we have developed an efficient method for erythro-selective epoxidation of acyclic allyl-substituted alkenes, including allylic alcohols, amines, and esters. Up to 9:1 erythro selectivities for terminal allyllic alkenes could be achieved, which are significantly higher than that achieved using m-CPBA as an oxidant. In addition, the synthetic utilities of this epoxidation method were highlighted in stereoselective synthesis of key anti-HIV drug intermediates and epoxidation of glycals.
Stereospecific synthesis of phosphono-(1Z,3E)-dienyl compounds from β-phenyltelluro-vinylphosphonates and -vinylphosphine oxides
Braga, Antonio L.,Rhoden, Cristiano R.B.,Zeni, Gilson,Silveira, Claudio C.,Andrade, Leandro H.
, p. 35 - 40 (2003)
Phosphono-1,3-dienyl compounds 2 can be prepared by palladium cross-coupling reaction of β-phenyltelluro-vinylphosphonates or -vinylphosphine oxides with alkenes in the presence of a catalytic amount of PdCl2 and AcOAg as reoxidant agent at room temperature. The coupling reaction is stereospecific and the compounds 2 were obtained in good yields with total retention of configuration.
Highly dispersed nickel and palladium nanoparticle silica aerogels: Sol-gel processing of tethered metal complexes and application as catalysts in the Mizoroki-Heck reaction
Martinez, Sandra,Moreno-Manas, Marcial,Vallribera, Adelina,Schubert, Ulrich,Roig, Anna,Molins, Elies
, p. 1093 - 1097 (2006)
Highly dispersed Ni and Pd silica aerogels were prepared through sol-gel processes. They have been synthesized by tethering the metal to the silica matrix with the use of the complexing silanes AEAPTS [N-(aminoethyl)aminopropyl] trimethoxysilane or TRIAMIN [N-((aminoethyl)aminoethyl)aminopropyl] trimethoxysilane. The gels were dried with scCO2 to afford the aerogels. High metal dispersion and small particle sizes were observed through HRTEM and XRD measurements. The organic groups were removed by oxidation and/or pyrolysis. The Pd reduced aerogels containing 15-17% of palladium are good recoverable catalysts in the Mizoroki-Heck reaction. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
Preparation of α,β-Unsaturated Methyl Ketones from Diketene Using Bis(tributyltin) Oxide
Shibata, Ikuya,Nishio, Masahiro,Baba, Akio,Matsuda, Haruo
, p. 1219 - 1222 (1993)
Novel type tin enolate is easily formed by the regioselective ring cleavage of diketene with Bis(tributyltin) oxide .The enolate caused carbon-carbon bond formation with aldehydes.As a result, α,β-unsaturated methyl ketones were obtained in good yields, accompanied by decarboxylation.
