نتایج جستجو برای: metathesis of ethylene
تعداد نتایج: 21167453 فیلتر نتایج به سال:
A tandem olefin metathesis/oxidative cyclization has been developed to synthesize 2,5-disubstituted tetrahydrofuran (THF) diols in a stereocontrolled fashion from simple olefin precursors. The ruthenium metathesis catalyst is converted into an oxidation catalyst in the second step and is thus responsible for both catalytic steps. The stereochemistry of the 1,5-diene intermediate can be controll...
A direct and scalable route to γ-keto-α,β-unsaturated esters, useful intermediates in medicinal chemistry and natural products synthesis, is reported. The key step involves the use of Grubbs' second-generation olefin metathesis catalyst for cross-metathesis of alkyl acrylates and 2° allylic alcohols. The metathesis step is followed by oxidation to give the desired products in high yield on scal...
The literature of olefin metathesis by heterogeneous supported catalysts, both industrial-type supported metal oxides (ReOx/Al2O3, ReOx/(SiO2−Al2O3), MoOx/SiO2, MoOx/Al2O3, MoOx/(SiO2−Al2O3), WOx/SiO2, and WOx/ (SiO2−Al2O3)) and supported organometallic complexes, is comprehensively reviewed. The focus of this Review is supported metal oxide catalysts, but the well-defined supported organometal...
Dicarboxylic acids derived from plant oils are attractive intermediates for the synthesis of polymer materials. Similar to polyethylene, the incorporation of long methylene sequences enables polymer crystallization and renders polyesters hydrophobic. Long-chain aliphatic polyesters that incorporate the full length of the plant oil methylene sequences possess high melting points (Tm > 100 °C) an...
The first application of olefin cross-metathesis with vinylchlorins and vinylporphyrins using a "second generation" Grubbs' catalyst is reported. Cross-metathesis products were obtained in good yields with high E-stereoselectivity.
This communication describes the total synthesis of the marine polyether toxin, gambierol. This work couples our iterative C-glycoside/enol ether-olefin metathesis strategy to the subunits with a unique olefin metathesis/carbonyl olefination reaction to bring the subunits together.
A novel synthetic route to spirocyclic thiazolidinediones is reported by utilizing ring-closing metathesis (RCM). A selective cross metathesis (CM) of N-allyl azaspiro derivatives with different olefins has been demonstrated to prepare substituted azaspiro-[4.4]nonenediones. The X-ray crystal structure of a spirocyclic thiazolidinedione dimer is described, which has been prepared in two steps f...
Metallacyclobutanes are an important class of organometallic intermediates, due to their role in olefin metathesis. They can have either planar or puckered rings associated with characteristic chemical and physical properties. Metathesis active metallacyclobutanes have short M-Cα/α' and M···Cβ distances, long Cα/α'-Cβ bond length, and isotropic 13C chemical shifts for both early d0 and late d4 ...
This paper presents a computational analysis of metathesis patterns that distinguishes three categories of metathesis that differ in their computational complexity. These categories are local metathesis, bounded long distance metathesis, and unbounded long distance metathesis. Using the formalism of finite state automata, it is established that the first two categories are subsequential, while ...
The process of ethylene production from ethane dehydrogenation is one of the interesting processes in the field of conversion the petroleum light gases to the valuable products. In this process, the outlet gaseous product is a combination of ethylene, ethane and hydrogen. Effective separation techniques are required for separation of ethylene from unreacted ethane. Here a new adsorbent approach...
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