Search results for "Catalysis"

ChemInform Abstract: Gold-Catalyzed Intramolecular Hydroamination of o-Alkynylbenzyl Carbamates: A Route to Chiral Fluorinated Isoindoline and Isoqui…

2013

Title compounds are prepared in enantiomerically pure form by the diastereoselective addition of fluorinated nucleophiles to N-(tert-butanesulfinyl)imines (I) followed by a sequence of Sonogashira cross-coupling/gold(I)-catalyzed cycloisomerization of the corresponding carbamate.

Optimization Strategies for the Anodic Phenol‐Arene Cross‐Coupling Reaction

2021

ChemInform Abstract: Enantioselective Synthesis of 4-Substituted Dihydrocoumarins Through a Zinc Bis(hydroxyamide)-Catalyzed Conjugate Addition of Te…

2013

Terminal alkynes (II) react with coumarins (I) in the presence of diethylzinc and chiral bis(hydroxyamide) ligands to give enantiopure dihydrocoumarins (III) substituted with an alkynyl group in C(4) position in good enantioselectivities.

Regioselektive Zinn(II)chlorid-induzierte N-Aralkoxy-alkylierung am 2,3-Dimethylindol

1986

2,3-Dimethylindole (1) reacts by tin(II)chloride catalysis with arylaldehydes in dichloromethane, which contains 0.2% ethanol, regioselectively to the indol-1-yl-aryl-ethoxy-methanes3 a, 3 b.

ChemInform Abstract: Enantiocontrol in the Intermolecular Cyclopropanation Reaction Catalyzed by Dirhodium(II) Complexes with ortho-Metalated Aryl Ph…

2010

(P) and (M) dirhodium(II) complexes with ortho-metalated aryl phosphines are assessed as chiral catalysts in the enantioselective cyclopropanation of styrenes by ethyl diazoacetate; enantioselectivities up to 91% and up to 87%, respectively, for cis- and trans-2-arylcyclopropanecarboxylates are observed.

Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxide catalysts

2004

Abstract MoVTeNbO catalysts, prepared by hydrothermal synthesis, are active and highly selective in the ODH of ethane, especially those with a MoVTeNb molar ratio of 1–0.15–0.16–0.17 and heat-treated at 600–650 °C. On the best catalyst, selectivities higher than 80% at ethane conversion levels higher than 80% have been obtained operating at relatively low reaction temperatures (340–400 °C). Thus, yields of ethylene of ca. 75% have been obtained, which exceeds the best yield reported in the literature. Te 2 M 20 O 57 ( M =Mo, V, Nb) and (V,Nb)-substituted θ -Mo 5 O 14 , in addition to small amounts of the Te 0.33 M O 3.33 ( M =Mo, V, Nb) phase, can be proposed in the most selective cataly…

Polymerization of ethylene and propylene with ziegler-natta catalysts

2007

ChemInform Abstract: Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

2016

Above 31.1 °C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO2) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO2 is presented.

1,7-Octadiene-Assisted Tandem Multicomponent Cross-Enyne Metathesis (CEYM)-Diels-Alder Reactions: A Useful Alternative to Mori’s Conditions

2012

The use of 1,7-octadiene as an in situ source of ethylene led us to develop a novel multicomponent tandem cross-enyne metathesis (CEYM)-Diels-Alder reaction. The process can be considered a relay metathesis, in which the ethylene liberated in the ring-closing metathesis (RCM) of 1,7-octadiene initiates the tandem sequence. Aliphatic, aromatic, and fluorinated alkynes and several dienophiles are compatible with the process, which is particularly efficient with aromatic alkynes. This methodology constitutes a useful variant of Mori's conditions in CEYM-related reactions.

Selective oxidation of propane and ethane on diluted Mo–V–Nb–Te mixed-oxide catalysts

2007

Abstract Te-free and Te-containing Mo–V–Nb mixed oxide catalysts were diluted with several metal oxides (SiO 2 , γ -Al 2 O 3 , α -Al 2 O 3 , Nb 2 O 5 , or ZrO 2 ), characterized, and tested in the oxidation of ethane and propane. Bulk and diluted Mo–V–Nb–Te catalysts exhibited high selectivity to ethylene (up to 96%) at ethane conversions 10 % , whereas the corresponding Te-free catalysts exhibited lower selectivity to ethylene. The selectivity to ethylene decreased with the ethane conversion, with this effect depending strongly on the diluter and the catalyst composition. For propane oxidation, the presence of diluter exerted a negative effect on catalytic performance (decreasing the forma…