نتایج جستجو برای: pyridines
تعداد نتایج: 6741 فیلتر نتایج به سال:
Condensation of two molecules of pyridine-2-carboxaldehyde (pyca), in the presence of MnCl(2) and ammonium diethyldithiophosphate, produced, in a one-pot reaction, Mn(II) complexes containing 3-(pyridin-2-yl)imidazo[1,5-a]pyridines as κ(2)(N,N) chelate ligands which could be easily separated from the metal, this being a convenient way to pyridyl-aza-indolizine heterocycles.
A novel four-component strategy for the selective synthesis of fused azepino[5,4,3-cd]indoles and pyrazolo [3,4-b]pyridines has been established. The bond-forming efficiency, accessibility of starting materials and substrate scope provide invaluable access to tetra-, and bis-heterocyclic scaffolds.
An isothiourea-catalyzed Michael addition-lactamization followed by the sulfide oxidation-elimination/N- to O-sulfonyl transfer sequence for the formation of 2,3,5- and 2,3-substituted pyridine 6-tosylates from (phenylthio)acetic acids and α,β-unsaturated ketimines is described. Incorporation of the valuable 2-sulfonate group allows derivatization to a range of di-, tri-, and tetrasubstituted p...
A new methodology has been developed for the synthesis of pyridines from allyl amines and alkynes, which involves sequential Cu(II)-promoted dehydrogenation of the allylamine and Rh(III)-catalyzed N-annulation of the resulting α,β-unsaturated imine and alkyne.
The Sandmeyer reaction of differently C-2 substituted N-(prop-2-yn-1-ylamino)pyridines is an efficient, mild, new and practical method for the stereospecific synthesis of (E)-exo-halomethylene bicyclic pyridones bearing the imidazo[1,2-a]pyridine heterocyclic ring system.
Trinuclear complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized using a ligand architecture based upon a 1,3,5-triarylbenzene core decorated with six pyridines and three alkoxide moieties. Characterization via X-ray diffraction, NMR, and magnetism studies is discussed.
An efficient reagent-controlled methodology for generating highly substituted diverse scaffolds from a common substrate has been developed; thus, treatment of a common precursor with different desilylating reagents, such as ammonium fluoride, caesium fluoride and PPTS, triggers different domino reaction sequences, yielding highly substituted pyridines, phenols and benzopyrans, respectively; the...
The one-pot four-component reaction of benzohydrazide (2-picolinohydrazide), acetylenedicarboxylate, isatins and malononitrile (ethyl cyanoacetate) with triethylamine as base catalyst afforded functionalized 1-benzamidospiro[indoline-3,4'-pyridines] in good yields. (1)H NMR spectra indicated that an equilibrium of cis/trans-conformations exist in the obtained products.
A simple metal-free, step-economic and selective access to pyridines from readily available substrates is reported, involving a flexible 4 A molecular sieves promoted Michael addition initiated domino three-component reaction between a 1,3-dicarbonyl, a Michael acceptor and a synthetic equivalent of ammonia.
Mechanistic studies of H2O2 activation by complexes related to [(BPMEN)Fe(II)(CH3CN)2](2+) with electron-rich pyridines revealed that a new intermediate formed in the presence of acetic acid with a 465 nm visible band can be associated with an unusual g = 2.7 EPR signal. We postulate that this chromophore is an acylperoxoiron(III) intermediate.
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