نتایج جستجو برای: hantzsch reaction

تعداد نتایج: 412554  

Journal: :Chemical communications 2011
Christopher G Evans Umesh K Jinwal Leah N Makley Chad A Dickey Jason E Gestwicki

A series of dihydropyridines were identified that have an effect on the accumulation of tau, an important target in Alzheimer's disease. The dihydropyridine collection was expanded using the Hantzsch multicomponent reaction to develop preliminary structure-activity relationships.

2005
C. Hak C. Ordóñez A. S. H. Prévôt W. Junkermann

Results from an intercomparison of several currently used in-situ techniques for the measurement of atmospheric formaldehyde (CH2O) are presented. The measurements were carried out at Bresso, an urban site in the periphery of Milan (Italy) as part of the FORMAT-I field campaign. Eight instruments were employed by six independent research groups using four different techniques: Differential Opti...

A protocol for the synthesis of 1,4-dihydropyridines (Hantzsch type-products) was developed by means of a three-component condensation of an aldehyde, a β-dicarbonyl compound, ammonium acetate and nano Al2O3/KF as catalyst. This reaction was carried out under different conditions including i) solvent-free ii) and reflux in different solvents. In all conditions, the desired products were obtaine...

Journal: :Chemical Communications 2021

The Hantzsch reaction was adapted to allow the rapid radiosynthesis of 13N-labelled 1,4-dihydropyridines, including [13N]nifedipine, for preclinical PET imaging.

Herein, it has been shown that the bismuth ferrite magnetic nanoparticles (BFO-MNPs) are new, efficient and recyclable catalysts for the synthesis of polyhydroquinoline derivatives by the Hantzsch reaction. The one-pot four-component cyclocondensation reaction of dimedone, aromatic aldehydes, ethyl acetoacetate and ammonium acetate was carried out under solvent-free conditions. The...

2014
J. Kaiser X. Li R. Tillmann I. Acir F. Holland F. Rohrer R. Wegener F. N. Keutsch

Two gas-phase formaldehyde (HCHO) measurement techniques, a modified commercial wet-chemical instrument based on Hantzsch fluorimetry and a custombuilt instrument based on fiber laser-induced fluorescence (FILIF), were deployed at the atmospheric simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber) to compare the instruments’ performances under a rang...

Journal: :Chemical & pharmaceutical bulletin 2008
Sanjeeva Reddy Cherkupally Raghu Mekala

A facile and efficient synthetic route to polyhydroquinolines has been developed via four-component condensation reactions of aldehydes, dimedone, ethyl acetoacetate and ammonium acetate in the presence of p-toluenesulfonic acid (p-TSA) catalyst in ethanol at ambient temperature through Hantzsch reaction. Simple work-up procedure, environmentally friendly, inexpensive and non-toxic catalyst, sh...

Journal: :Angewandte Chemie 2017
Xiao-Long Xu Zhi Li

Allylation and benzylation of p-quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel-Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The ...

Journal: :Chemical communications 2015
Emilie Martinelli Anna Chiara Vicini Michele Mancinelli Andrea Mazzanti Paolo Zani Luca Bernardi Mariafrancesca Fochi

In the presence of a thiourea catalyst, β-CF3 nitroalkenes react with Hantzsch esters in a highly enantioselective fashion, giving a broad range of β-CF3 amine precursors with a tertiary stereocentre at the β-position. This reaction represents the first general catalytic enantioselective approach to this important class of β-CF3 amines.

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