Search results for " organic"

Direct arylation of heteroaromatic compounds with congested, functionalised aryl bromides at low palladium/triphosphane catalyst loading.

2011

International audience; A new ferrocenyl triphosphane ligand associated to palladium was found to be an efficient catalyst for the direct coupling of highly congested, functionalised aryl bromides with a variety of heteroarenes. These coupling reactions can generally be performed by using a low-loading (0.1-0.5 mol%) of the catalyst. The present protocol tolerates important and useful functional groups, which allows for further elaboration into more sophisticated heterocyclic molecules. The straightforward arylation of heteroaromatic compounds with congested ortho-substituted aryl bromides may permit further convergent syntheses of diverse ligands, biologically active molecules and molecula…

Crystal structure of diethyl 2-amino-5-{4-[bis-(4-methyl-phen-yl)amino]-benzamido}-thio-phene-3,4-di-carboxyl-ate.

2019

The title compound forms a head-to-head centrosymmetric dimer, involving a pair of inter­molecular N—H⋯O hydrogen bonds. It also forms two intra­molecular bonds between its amine and amide and the ester carbonyl groups.

Organocatalysts Fold to Generate an Active Site Pocket for the Mannich Reaction

2017

Catalysts containing urea, thiourea and tertiary amine groups fold into a three-dimensional organized structure in solution both in the absence as well as in the presence of substrates or substrate analogues, as indicated by solution NMR and computational studies. These foldamer catalysts promote Mannich reactions with both aliphatic and aromatic imines and malonate esters. Hammett plot and secondary kinetic isotope effects provide evidence for the C-C bond forming event as the turnoverlimiting step of the Mannich reaction. Computational studies suggest two viable pathways for the C-C bond formation step, differing in the activation modes of the malonate and imine substrates. The results sh…

Reactivity of 4-Aminopyridine with Halogens and Interhalogens : Weak Interactions Supported Networks of 4-Aminopyridine and 4-Aminopyridinium

2019

The reaction of 4-aminopyridine (4-AP) with ICl in a 1:1 molar ratio in CH2Cl2 produced the expected charge-transfer complex [4-NH2-1λ4-C5H4N-1-ICl] (1·ICl) and the ionic species [(4-NH2-1λ4-C5H4N)2-1μ-I+][Cl–] (2·Cl–) in a 2:1 relation, as indicated by 1H NMR spectroscopy in solution. In contrast, only the ionic compound [(4-NH2-1λ4-C5H4N)2-1μ-I+][IBr2–] (2·IBr2–) was observed in the analogous reaction with IBr. The reaction between 4-AP and I2 in a 1:1 molar ratio also afforded two components, one of which was identified as the congeneric cation in [(4-NH2-1λ4-C5H4N)2-1μ-I+][I7–] (2·I7–) that contains a polyiodide anion as a result of transformation in a 1:2 molar ratio between the starti…

Self-assembly mechanism based on charge density topological interaction energies

2017

The packing interactions have been evaluated in the context of the self-assembly mechanism of crystal growth and also for its impacts on the aromaticity of the trimesate anion. The structure of ethylammonium trimesate hydrate (1) measured at 100 K and a charge density model, derived in part from theoretical structures, is reported. Theoretical structure factors were obtained from the geometry-optimized periodic wave function. The trimesic acid portion of 1 is fully deprotonated and participates in a variety hydrogen bonding motifs. Topological analysis of the charge density model reveals the most significant packing interactions and is then compared to a complementary analysis performed by …

Mononuclear rearrangement of heterocycles in ionic liquids catalyzed by copper(II) salts

2008

Abstract The reactivity of E- and Z-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole in the presence of CuCl2 and Cu(ClO4)2·6H2O has been studied in four imidazolium ionic liquids [bmim][X] (X=BF4−, PF6−, SbF6− and CF3SO3−). The reaction may follow different mechanistic patterns, depending on the nature of the ionic liquid anion, accounting for both qualitative and kinetic data. In the presence of CuCl2, two processes take place at the same time, i.e., the E⇆Z isomerization and the rearrangement of Z-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole. In contrast, in the presence of Cu(ClO4)2·6H2O, the rearrangement occurs only in solution of [bmim][BF4] and [bmim][C…

[bmim][F] a TSIL differently acting on aromatic nuclei

How mixing ionic liquids affects a Diels-Alder reaction

On the characterization of some [bmim][X]/co-solvent binary mixtures: a multidisciplinary approach by using kinetic, spectrophotometric and conductom…

2008

Abstract In order to study the intrinsic characteristics and to evaluate the structural variations determined by the addition of a co-solvent to 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4 ]) we examined the behaviour of some probes in [bmim][BF 4 ]/co-solvent binary mixtures. The rate constants of the piperidino-catalyzed rearrangement of the Z -phenylhydrazone of the 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole as well as the spectrometric properties of pyrene and Nile Red were evaluated. With the same purpose also 1 H NMR and conductivity measurements were carried out. By comparison the behaviour of 1-butyl-3-methylimidaz…

Ionic liquid binary mixtures: Promising reaction media for carbohydrate conversion into 5-hydroxymethylfurfural

2014

Abstract The conversion of carbohydrates into 5-hydroxymethylfurfural (5-HMF) has been studied in binary mixtures of ionic liquids (ILs), using strongly acidic resin Amberlyst 15 as the catalyst. In particular, both mono- and disaccharides, such as fructose, glucose and sucrose have been investigated. Considering the favorable effect exerted by chloride-based ionic liquids in the dissolution of carbohydrates, we used binary mixtures of 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) with [bmim + ] based ionic liquids differing in size, shape and coordination ability of the anion ([bmim][BF 4 ], [bmim][N(CF 3 SO 2 ) 2 ], [bmim][N(CN) 2 ], [bmim][SbF 6 ] and [bmim][CF 3 SO 3 ]). Carbohydrat…