Five-component synthesis of dihydropyridines based on diketene

A novel five-component strategy involving commercially available diketene, primary amines, malononitrile and various benzaldehydes for the synthesis of densely functionalized 1,4-dihydropyridines in good yields was achieved. The reaction pathway involves a sequential ring-opening of diketene/enamine formation/Knoevenagel-condensation/Michael addition and 6-exo-tet cyclization, resulting in multiple bond-formation events including two C–C and three C–N bonds ultimately leading to the formation of the respective 1,4-dihydropyridines.     

Chromium(III), manganese(II) and iron(III) complexes based on hydrazone Schiff-base and azide ligands: synthesis,crystal structure and antimicrobial activity

A tridentate NNO donor hydrazine Schiff base, HL, was obtained from condensation of pyridine 2-carbaldehyde and 4-hydroxy benzohydrazide. HL and azide ligands with Cr(III), Mn(II) and Fe(III) have been used to synthesize [Cr(L)(N₃)(OCH₃)]₂ (1), [Mn(HL)₂(N₃)₂] (2), and [Fe(L)(N₃)(OCH₃)]₂·H₂O (3). HL is quite diverse in its chelating ability and can be a neutral or monoanionic ligand as a tridentate unit. In this paper, we report structures showing different denticities of the ligand having different charges. The ligand 1–3 was characterized by elemental analysis, FT-IR, and UV–vis spectral studies and solid-state structures were determined by single-crystal X-ray diffraction analysis, revealing that 1 and 3 are binuclear, while 2 is mononuclear. The efficiencies of the ligand and the three complexes were evaluated for antimicrobial activity; MIC data revealed that HL 1–3 are not strongly active in comparison to standard drugs.     

Tosylmethylisocyanide (TosMIC) [3+2] cycloaddition reactions: A facile Van Leusen protocol for the synthesis of the new class of spirooxazolines,spiropyrrolines and Chromeno[3,4-c]pyrrols

The reactivity and chemo-, regio- and diastreo-selectivity of tosylmethyl isocyanides (TosMIC) are investigated in Van Leusen type [3 + 2] cycloaddition reactions with the various activate cyclic ketones and double CC bonds in the synthesis of spirooxazolines, spiropyrrolines and chromeno[3,4-c]pyrrols in good to excellent yields under catalyst-free conditions without any activation at ambient temperature.     

One-step Synthesis of 3,4-Dihydrobenzimidazo[2,1-<Emphasis Type="Italic">b</Emphasis>]quinazolin-1(2<Emphasis Type="Italic">H</Emphasis>)-ones in an Ionic Liquid

Summary.  A novel class of 3,4-dihydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones was synthesized in very short reaction times with good yields in the presence of 3-butyl-1-methyl imidazolium bromide as a room temperature ionic liquid at 120°C. The ionic liquid can be recycled for subsequent reactions without any loss of efficiency.     

A facile three- and four-component procedure toward the synthesis of functionalized pyrano- and benzo[f]quinoxaline derivatives

A two-step procedure has been used to synthesize quinoxaline derivatives in the presence of a catalytic amount of triethylamine. Products can be separated from the reaction media by simple filtration. When EtOH was used as a solvent, the reaction proceeded via a three-component pathway, but in the presence of MeOH (as a solvent or in a 1-equivalent) the reaction proceeded via a four-component pathway.     

A Novel Metal–Ligand Iodo‐bridged Lead(II) Compound: Synthesis,Crystal Structure,Thermal Properties,and DFT Calculations of [Pb(dmp)I2]n

. A novel 1D Pb^II coordination polymer [Pb(dmp)I₂]_n ( 1 ) (dmp = 2,9‐dimethyl‐1,10‐phenanthroline) containing a Pb₂‐(μ‐I)₂ unit was synthesized and characterized by elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopy and studied by thermal analysis as well as X‐ray crystallography. The single‐crystal X‐ray data show that the coordination number of Pb^II ions is six, i.e. PbN₂I₄, with “stereo‐chemically active” electron lone pairs, and the coordination sphere is asymmetrical. They also show that the chains interact with each other through π‐π stacking interactions, which create a 3D framework. The structure of the title complex has been optimized by density functional theory calculations. The calculated structural parameters and the IR spectra of the title complex are in agreement with the crystal structure.     

TETRABUTYLAMMONIUM HYDROGEN SULFATE: AN EFFICIENT CATALYST FOR THE SYNTHESIS OF 3,4-DIHYDROPYRIMIDIN-2(1H)-ONES UNDER SOLVENT-FREE CONDITIONS

Tetrabutylammonium hydrogen sulfate (TBAHS) as[3pc] a solid protic acid and phase-transfer reagent catalyzed the three-component condensation reactions of aldehydes, 1,3-dicarbonyl compounds, and urea or thiourea under solvent-free conditions leading to 3,4-dihydropyrimidin-2(1H)-ones in high yields at 80°C.     

Sonochemical Synthesis of a Novel Nanoscale Lead(II) Coordination Polymer: Synthesis,Crystal Structure,Thermal Properties,and DFT Calculations of [Pb(dmp)(μ‐N3)(μ‐NO3)]n with the Novel Pb2(μ‐N3)2(μ‐NO3)2 Unit

A new nanostructured coordination polymer of divalent lead with the ligand 2,9‐dimethyl‐1,10‐phenanthroline (dmp), [Pb(dmp)(μ‐N₃)(μ‐NO₃)]_n ( 1 ), was synthesized by sonochemical methods. The polymer was characterized by scanning electron microscopy, X‐ray powder diffraction, IR, ¹H NMR, and ¹³C NMR spectroscopy, and elemental analyses. Compound 1 was structurally characterized by single‐crystal X‐ray diffraction. The single‐crystal analysis shows that the coordination number of Pb^II ions is seven, (PbN₄O₃) has a “stereo‐chemically active” electron lone pair, and the coordination sphere is hemidirected. The chains interact with each other through π–π stacking interactions to create a 3D framework. The structure of the title complex was optimized by density functional calculations. The calculated structural parameters and the IR spectrum of the title complex are in agreement with the crystal structure.