Chemoselective synthesis of novel aminoindolizines using aminopyridines, acetylenic diesters and α-halo ketones

A chemoselective synthesis of novel indolizine derivatives were reported via three-component reactions of aminopyridines, acetylenic diesters and a-halo ketones. In these reactions, the zwitterion generated from aminopyridines and acetylenic diesters reacted with a-halo ketones to produce indolizine skeleton in good to high yields under mild reaction conditions.

Enantioselective epoxidation of olefins with hydrogen peroxide catalyzed by bioinspired aminopyridine manganese complexes derived from L-proline

Three chiral aminopyridine ligands derived from L-proline were prepared. Careful evaluation of the corresponding aminopyridine manganese complexes in asymmetric epoxidation of olefins revealed a broad substrate scope in the presence of 0.2 mol% manganese complex and 0.5 equiv. 2,2-dimethylbutyric acid, with aqueous hydrogen peroxide as an oxidant. A variety of olefins including styrenes, chromenes, and cinnamamides were transformed successfully into the target epoxides with moderate to excellent enantioselectivity（yield up to 95%, ee up to 99%）.

Three-component Reaction of Aromatic Aldehyde,Malononitrile and Aliphatic Amine Leading to Different Pyridine Derivatives

The three-component reaction of aromatic aldehyde,malononitrile and aliphatic amine in a mixed solvent of methanol and water exhibited very interesting molecular diversity and gave the derivatives of polysubstituted N-methyldihydropyridines,2-dialkylaminopyridines and 2-methoxypyridines as main products according to the structure of aliphatic amines used.

Synthesis of Pyridylazo-substituted Chromogenic Calix[4]arenes

This letter reports a novel method for preparing chromogenic calix[4]arenes, in which the 4-aminopyridine was diazotized with isoamyl nitrite in EtONa/EtOH, and mono(azo)-, bis(azo)- and tetra(azo)-substituted calix[4]arenes were obtained as main product respectively by diazo-coupling in different molar ratio to calix[4]arene in non-aqueous solution at 0-5 degrees.

Syntheses and Characterization of Two Diiron Dithiolate Complexes Containing 4-Dimethylaminopyridine

Two diiron dithiolate complexes, （μ-pdt）Fe2（CO）5（C7H10N2） 3 and （μ-edt）-Fe2（CO）5（C7H10N2） 4 （pdt = -S（CH2）3S-, edt = -S（CH2）2S-）, have been synthesized and characterized by single-crystal X-ray diffraction. Complex 3 crystallizes in the monoclinic system, space group P21/c with a = 10.168（4）, b = 11.816（4）, c = 16.595（7） and β = 95.195（6）o; and complex 4 crystallizes in the orthorhombic system, space group P212121 with a = 9.317（3）, b = 11.898（4）, c = 34.006（10） .The distances of Fe（1）–Fe（2） are 2.5058（9） in 3 and 2.4942（10） in 4, falling in the normal range of Fe–Fe bond length （2.49～2.57 ）. The cyclic voltammograms show that 3 and 4 display irreversible reduction peaks （FeIFeI/ FeIFe0） at –1.717 V and –1.673 V vs. Ag/AgCl, respectively. With different acids, complex 3 has distinguishable behavior, two protonations in addition of HBF4-Et2O and single protonation besides HOAc-CH3CN, and complex 4 has a similar action to 3 with HOAc-CH3CN for a semblable structure.

Crystal Packing Studies, Thermal Properties and Hirshfeld Surface Analysis in the Zn(II) Complex of 3-Aminopyridine with Thiocyanate as Co-Ligand

Reaction of zinc acetate, potassium thiocyanate and the ligand 3-ampy gave the discrete tetrahedral complex [Zn(NCS)2(3-ampy)2] in which 3-ampy chelates in a monodentate fashion through its pyridine-N atom. It was characterized by single crystal X-ray diffraction, infrared, and elemental analysis. Density Functional Theory calculations were performed in order to gain insights into the role of weak molecular interactions in the complex that influence the self-assembly process and crystal packing. X---H (X = H, C, N and S) inter-actions. S-H interactions (30.2%) were found to be the main interactions that hold the molecules in the crystal structure. Furthermore, the thermolysis of the complex was studied in order to evaluate whether it was suitable as a precursor for zinc sulphide.

Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats

Objective To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it.Methods Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35?g*cm force (gcf), 70?gcf, 100?gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function. Results MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100?gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35?gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70?gcf injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1?mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely. Conclusions MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.

Synthesis and antibacterial activity of ethyl 2-amino-6-methyl-5-oxo-4-aryl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate

The three-component reaction of 4-hydroxy-l-methyl-2（1H）-quinolinone, aromatic aldehydes and ethyl cyanoacetate was carried out in the presence of a catalytic amount of 4-dimethyl aminopyridine （DMAP） in aqueous ethanol. The reactions result in the formation of pyranoquinoline derivatives in excellent yields. Antibacterial activity has been evaluated against Gram positive and Gram negative bacteria for some of the synthesized compounds. The results indicated that these compounds are moderately effective against bacterial growth and their effectiveness is highest against Pseudomonas aeruginosa.