Preparation of Chiral Amino Esters by Asymmetric Phase‐Transfer Catalyzed Alkylations of Schiff Bases in a Ball Mill

The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase‐transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified.     

Synthesis,structural characterization and biological studies of neodymium(III) and samarium(III) complexes with mercaptotriazole Schiff bases

A series of neodymium(III) and samarium(III) complexes of type [Ln(L)Cl(H₂O)₃] have been synthesized with Schiff bases (LH₂) derived from 3‐(phenyl/substituted phenyl)‐4‐amino‐5‐mercapto‐1,2,4‐triazoles and isatin. The structures of the complexes were established using elemental analysis, molar conductivities, magnetic moments, infrared, NMR (¹H, ¹³C) and UV–visible spectra, X‐ray diffraction and mass spectrometry. The thermal behaviour of these compounds under non‐isothermal conditions was investigated using thermogravimetry and differential thermogravimetry. The intermediates obtained at the end of various thermal decomposition steps were identified from elemental analysis and infrared spectral studies. All the ligands and their complexes were also screened for their antibacterial activity against Staphylococcus aureus and Bacillus subtilis and antifungal activity against Aspergillus niger, Aspergillus flavus and Colletotrichum capsici. The screening results were correlated with the structural features of the compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Liquid–liquid extraction of copper(II) with substituted salicylideneanilines from sulfate media

The liquid–liquid extraction of copper(II) with Schiff bases in chloroform from sulfate media is studied for pH and concentration of the extractant. Stoichiometry coefficients of the extracted species are determined by the slope analysis method. With salicylideneaniline, the copper(II) is extracted as a mixed chelate complex, CuL₂HL. In the presence of substituent, the copper is extracted as simple chelates, CuL₂. The trends in the values of extraction constants were explained in terms of the nature of the substituents.     

Spectral and computational chemistry studies for the optimization of geometry of dioxomolybdenum(VI) complexes of some unsymmetrical Schiff bases as antimicrobial agent

Abstract

This analysis highlights the design, spectroscopic characterization and quantum mechanical calculation of some new dioxomolybdenum(VI) complexes of some dibasic tetradentate Schiff bases. Ligands were derived from mono 5-bromosalicylaldehyde-orthophenylenediamine (^BrSal-OPD) and different 2-hydroxyketone derivatives. The characterization was performed by elemental analysis, FTIR, electronic, ¹H NMR and mass spectra, magnetic and molar conductance studies. Structure of the ligands and complexes were designed depending on experimental data and computational studies. According to all data, distorted octahedral geometry was proposed where oxygen atoms are in cis position. Prepared complexes exhibit moderate antimicrobial properties when evaluated against some pathogenic bacteria and fungi. Pharmacokinetic parameters were calculated to search their biological action, for example, absorption, distribution, metabolism, excretion, and toxicity.     

Syntheses and molecular structures of four inorganic–organic hybrid compounds from N-containing aromatic bases and perchlorometallates of Zn,Cu, Sn,and Fe

Four organic–inorganic crystals, [(HL1)₂(ZnCl₄)]·H₂O (1) (L1?=?2-methylquinoline), [(HL1)₂(CuCl₄)] (2), [(HL2)₂SnCl₆] (3) (L2?=?6-bromobenzo[d]thiazol-2-amine), and [(HL3)FeCl₄] (4) (L3?=?5,7-dimethyl-1,8-naphthyridine-2-amine), derived from N-containing aromatic Brønsted bases and metal(II) chlorides (zinc(II) chloride, copper(II) chloride dihydrate, tin(II) chloride dihydrate, and iron(III) chloride hexahydrate) were prepared at room temperature and characterized by IR, X-ray structure analysis, elemental analysis, and TG analysis. The crystals are built up by perchlorometallates (Zn, Cu, Sn, and Fe) associated with organic cations through multiple non-covalent associations. X-ray diffraction analysis reveals that 1 and 2 have 3-D network structures built from hydrogen bonds between the cations and chlorometallates. Water molecules play an important role in structure extension in 1. Anhydrous 3 and 4 produced from 2-aminoheterocyclic derivatives display 2-D sheet structures. Arrangements of anions and cations are dominated by shape and size of cations, and also by the different structures of the chlorometallates as well as non-bonding interactions in the crystal structures. Except for 1, the other compounds are thermally stable below 240°C.     

MCM‐41 Immobilized Acidic Functional Ionic Liquid and Chromium(III) Complexes Catalyzed Conversion of Hexose into 5‐Hydroxymethylfurfural

The development of novel methods to obtain biofuels and chemicals from biomass has been an immediate issue in both academic and industrial communities. In this work, a series of novel catalysts were prepared and characterized by FT‐IR , TGA , XRD , SEM , TEM , ICP‐AES , NH₃‐TPD and BET , which were applied for the conversion of hexose to 5‐hydroxymethylfurfural (HMF ). The Cr(Salten)‐MCM ‐41‐[(CH₂ )₃SO₃HVIm ]HSO₄ catalyst was the most active catalyst, and a glucose conversion of 99.8% with 50.2% HMF yield was obtained at 140 °C for 4 h in dimethyl sulfoxide (DMSO ). The effects of reaction temperature, reaction time, solvents and catalyst dosages were investigated in detail. MCM ‐41 immobilized acidic functional ionic liquid and chromium(III ) Schiff base complexes as heterogeneous catalysts can be easily recovered by simple filter treatment, exhibiting excellent stability and activity towards hexose conversion. Thus the heterogeneous catalysts were environment‐friendly for transforming biomass carbohydrates into fine chemicals.     

Novel Fluorinated Spiro [Indole-indazolyl-thiazolidine]-2,4′-diones: Design and Synthesis

The reaction of indol-2,3-diones ( 1a–i ) with 5-aminoindazole ( 2 ) has resulted in the formation of hitherto unknown 3-(indazol-5-yl)iminoindol-2-ones ( 3a–i ) in quantitative yields which, on 1,3-dipolar cyclocondensation with mercaptoacetic acid ( 4 ), has afforded a series of new spiro heterocycles, 3′-(indazol-5-yl) spiro[3H, indol-3, 2′ -thiazolidine]-2,4′-diones* ( 5a–i ).     

Synthesis and In Vitro Anti-HIV Activity of Some New Schiff Base Ligands Derived from 5-Amino-4-phenyl-4H-1,2,4-triazole-3-thiol and Their Metal Complexes

New Schiff base ligands (6–9) derived from 5-amino-4-phenyl-4H-1,2,4-triazole-3-thiol 1 and substituted benzaldehydes (2–5) as well as their metal complexes with Cu(II), Fe(II), Au(III), and Mn(II) (12–17) have been synthesized. A new benzothiazole derivative (11) was prepared from coupling of 7 with N-(benzothiazol-2-yl)-2-chloroacetamide 10. Their spectral properties were investigated. The newly designed and synthesized Schiff base ligands and the metal complexes were assayed for anti-HIV-1 and HIV-2 activity by examination of their inhibition of HIV-induced cytopathogenicity in MT-4 cells. Compounds 11 and 16 were found to be the most active inhibitors in cell culture (EC₅₀ = 12.2 μg/mL (SI = 4) and > 2.11 μg/mL (SI = > 1), respectively) against HIV-1, whereas 11 showed inhibition against HIV-2 of EC₅₀ > 10.2 μg/mL with SI = 9, which provided a good lead for further optimization.     

SYNTHESIS AND BIOLOGICAL ACTIVITIES OF NEW INDOLE DERIVATIVES CONTAINING SULFIDE AND/OR SULFONE MOIETIES. PART I

Abstract

4-Amino-halonitrodiphenyl sulfides(I) and/or 4-amino-halonitrodiphenyl sulfones have been found to react with isatin, N-acetyl isatin, isatin-N-Mannich bases, indole-3-carboxaldehyde and N-substituted indole-3-carboxaldehyde producing the corresponding indole derivatives. The biological activity of some of these products was screened against selected strains of bacteria.     

Generation of Phosphide Anions from Phosphorus Red and Phosphine in Strongly Basic Systems to Form Organylphosphines and -Oxides

Abstract

Generation of phosphide anions from phosphorus red or phosphine under the action of strong bases followed by their reactions with organyl halides, electrophilic alkenes and alkynes proves to be the most straightforward and well-controlled route to mono-, di- or triorganylphosphines or phosphine oxides of diverse structure.