نتایج جستجو برای: hantzsch reaction
تعداد نتایج: 412554 فیلتر نتایج به سال:
The use of diethyl carbonate as a sustainable solvent for organocatalytic asymmetric transfer hydrogenations of 2-substituted quinolines using highly efficient chiral phosphoric acid catalysts with Hantzsch esters as a hydrogen source is reported for the first time. The asymmetric transfer hydrogenation reaction in diethyl carbonate provides enantiomerically pure 1,2,3,4-tetrahydroquinolines wi...
A variety of Hantzsch 1,4-dihydropyridines were oxidized to their corresponding pyridines in high yields in the presence of Cu(C22H22N2O2) in refluxing acetic acid.
Under mechanical milling conditions, direct reductive benzylizations of malononitrile and 4-methylaniline by aromatic aldehydes were achieved using a Hantzsch 1,4-dihydropyridine as the reductant.
This work deals with the development of a new family of planar chiral phosphoric acids, based on a ferrocenophane/paracyclophane scaffold. The synthetic approach has been improved by taking advantage of a chiral phosphorylating agent to access enantiomerically enriched acids via diastereomers separation. These phosphoric acids have been used as catalysts for the enantioselective H-transfer redu...
A protocol for the isothiourea-catalysed transfer hydrogenation of ?,?-unsaturated para-nitrophenyl esters using Hantzsch ester has been developed. Good to excellent yields are observed aryl bearing electron-withdrawing ?-substituents. The products can either be isolated directly in moderate (7 examples, 16–98%) or converted corresponding methyl (2 68–70% yield) benzyl amides 44–88% after situ ...
Core@shell electrocatalysts for fuel cells have the advantages of a high utilization of Pt and the modification of its electronic structures toward enhancement of the activities. In this study, we suggest both a theoretical background for the design of highly active and stable core@shell/C and a novel facile synthetic strategy for their preparation. Using density functional theory calculations ...
sulfated titania nanoparticles (so42-/tio2 nps) were synthesized using titanium tetraisopropoxide (ttip) by the sol-gel method. the structure and morphology of the prepared nanocatalyst was characterized using x-ray diffraction (xrd), scanning electron microscopy (sem) and brunauer–emmett–teller (bet) methods as well as fourier transform infrared (ft-ir) and energy dispersive x-ray (edx) spectr...
A simple and mild one-pot three-component reaction for the preparation 1,4-dihydropyridines has been developed from various aldehyde substrates, 1,3-dicarbonyl compounds (dimedone) and ammonium acetate (Hantzsch method) in the presence of a catalytic amount of phospho sulfonic acid (PSA) as an efficient and heterogeneous solid acid in EtOH at room temperature. Preparation of PSA is straightforw...
Hantzsch esters (1,4-dihydropyridine dicarboxylates) have become, in this century, very versatile reagents for enantioselective organic transformations. They can act as hydride transfer agents to reduce, regioselectively, a variety of multiple bonds, e.g., C=C and C=N, under mild reaction conditions. are excellent the dearomatization heteroaromatic substances, participate readily cascade proces...
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