نتایج جستجو برای: lewis acid catalyst
تعداد نتایج: 798753 فیلتر نتایج به سال:
Iron (III) phthalocyanine complexes were employed for the first time as a mild and efficient Lewis acid catalyst in the selective oxidation of cyclohexene to cyclohexane-1,2-diol. It was found that the catalyst FePcOTf shown excellent conversion and moderate selectivity relative to other iron (III) phthalocyanine complexes. The optimum conditions of the oxidation reaction catalyzed by FePcOTf/H...
چکیده ندارد.
Bi(OTf)(3)·nH(2)O was found to be an efficient promoter of the cyclisative hydroamination of unactivated alkenyl sulfonamides, giving rise to the N-protected 2-methyl pyrrolidines in good to excellent yields (up to 95%). Based on control experiments, a joint Lewis acid-Brønsted acid catalysis might be in operation, or triflic acid itself, generated in situ by hydrolysis of metal triflate, could...
In this research we used Heavy Propylene Tetramer (HPT) and A1C13 —BF3 (Lewis acids) ascatalyst and ethanol, n-propanol and n-butanol as co-catalyst. Using Lewis acids as catalyst, theHPTs form molecules with higher molecular weight. Since the raw materials of the reaction are byproducts of other reactions, are not pure and contain various compounds with different M.W andalso different chemical...
The development of transition-metal-catalyzed asymmetric hydrogenation could be stated as the cradle of modern enantioselective catalysis. Since the early asymmetric hydrogenation example from Knowles and Sabacky in 1968, the method has rapidly advanced over the years into an important tool in academia and chemical industry. In general, for these transformations the development of effective tra...
Since the innovative work of Terada and Akiyama, asymmetric reaction using chiral Brønsted acid has attracted great attention. Asymmetric aldol reactions are extensively studied in different organocatalysis. acid-catalyzed may be carried out directly without modification substrates or Mukaiyama type silyl enol ether as nucleophiles. The proceed through formation intermediate followed by attack ...
Production of 5-hydroxymethylfurfural (HMF) from biomass-derived glucose has great potential for synthesis renewable fuels and chemicals. Selective conversion to requires a balance between Lewis Brønsted acids the cascade isomerization followed by fructose dehydration. A dual Brønsted-Lewis acid, phosphotungstic acid encapsulated MIL-101(Al)–NH2 metal–organic frameworks (MOFs) was developed cat...
A multi-component polyoxometalate based on earth-abundant elements (NH4)10[Co8(H2O)10V10Mo23O104(OH)6]·34.5H2O () has been successfully obtained and characterized. Furthermore, compound acted as a Lewis acid catalyst and promoted the conversion of carbon dioxide to a cyclic carbonate under mild reaction conditions.
We have developed a versatile strategy to access dihydropyrazoles in highly enantioenriched form. Dipolar cycloaddition of electron-deficient acceptors and in situ-generated nitrile imines proceeds with high regio- and enantioselectivity using 10 mol % chiral Lewis acid catalyst. A variety of dihydropyrazoles that incorporate functionality for further manipulation have been prepared.
The asymmetric aza-Diels-Alder reaction of chiral imines with Danishefsky's diene in chiral ionic liquids provides the corresponding cycloadduct with moderate to high diastereoselectivity. The reaction has proved to perform better at room temperature in ionic liquids without either Lewis acid catalyst or organic solvent. Chiral ionic liquids are recycled while their efficiency is preserved.
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