Synthesis,structure and characterization of some Schiff bases bearing phenylferrocene

Some novel Schiff bases bearing phenylferrocene were synthesized by condensation reaction of 4‐ferrocenylaniline with different aromatic aldehydes. The compounds prepared were characterized by spectroscopic methods (IR, UV–visible, ¹H and ¹³C NMR) and elemental analysis. The single crystal analysis of compound F1 [monoclinic, space group, P2₁/c (no. 14), a = 19.858(2), b = 7.416(2), c = 12.095(5) Å, β = 106.257(14) ] indicates a trans imine bond with a bond length of 1.270(2) Å, typical of a carbon‐nitrogen double bond. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of liquid crystal ferrocene derivatives and their complexes with Cu2+

A series of liquid crystal ferrocene-containing Schiff bases of general formula C₅H₅FeC₅H₄-C₆H₄-N=CN-(X)C₆H₃-O(O)-C₆H₄-OC_nH_2n+1 (X=H, OH, n=3–12) was obtained, together with several analogs, 1,1-bis-substituted at the ferrocene fragment, having a thermotropic nematic mesophases. Derivatives with X=OH were used to obtain Cu²⁺ chelate complexes, of which the compounds with n=10 and n=12 displayed nematic liquid crystalline properties.Physicotechnical Institute, Kazan Scientific Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 402–407, February, 1992.     

Synthesis,characterization, electrochemistry and evaluation of biological activities of some ferrocenyl Schiff bases

Synthesis of ferrocenyl Schiff bases ( 1–6 ) was carried out by the condensation reaction of 4‐ferrocenyl aniline with different substituted aromatic aldehydes and acetyl acetone. Compounds were characterized by physical measurements, elemental analysis, FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopy. Single crystal X‐ray analysis of compound 2 showed the co‐planarity of both aromatic rings connected by a C–N double bond. Compounds demonstrated reversible one‐electron redox behavior and their peak currents were found to increase linearly with the square root of the sweep rate ν^1/2. The overall electrode processes were found to be diffusion controlled. Compounds 1 and 4 showed low cytotoxicity and appreciable antifungal, antioxidant and DNA protection activities. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal stability of some ferrocene containing schiff bases

Taking into account the importance of thermal stability in the liquid crystals field, the study presents the thermal behavior of some ferrocene containing Schiff bases. Some other kinetic characteristics, such as reaction order (n), activation energy (E _a) and pre-exponential factor (lnA) have been also evaluated. The thermal stability series of Schiff bases was established analysis associated with three parameters (T _d, T _max, E _a) is: S₆<S₄<S₃<S₅<S₁<S₂.     

Synthesis and antimicrobial activities of some novel 1,2,4-triazole derivatives

In the present investigation, a series of new Schiff bases 4a–f were synthesized by the condensation of N-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-4-substituted-benzamides 3a–b with various substituted aromatic aldehydes in ethanol–dioxane mixture using catalytic amount of sulfuric acid. The starting materials 3a–b were in turn synthesized by the fusion of benzoyl glycine/substituted benzoylglycine with thiocarbohydrazide. Newly synthesized compounds were characterized by IR, NMR, mass spectra and elemental analyses. All the compounds were evaluated for their antibacterial and antifungal activity using the Minimum Inhibition Concentration (MIC) method by serial dilution technique. Few of the compounds were found to be biologically active.     

Iridium(iii)-(hydrido)cyclometallated-imine complexes and metal-promoted hydrolytic cleavage of imines

The room temperature reaction of the complex cis,trans,cis-[Ir(H)₂(PPh₃)₂(Solv)₂]PF₆ (Solv is a solvent) with the imine PhCH₂N=CHPh in acetone generates (with loss of H₂) the orthometallated complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(Me₂CO)]PF₆ (3) containing a five-membered cyclometallated imine moiety. In MeOH, the reaction at an imine : Ir ratio = 1 leads to the corresponding MeOH analog of 3, while with excess imine, the mixed orthometallated imine/bezylamine complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(PhCH₂NH₂)]PF₂ (4) is formed; the source of the coordinated amine is an Ir-promoted hydrolysis of the imine, the water likely coming from imine. Complexes 3 and 4 are fully characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectroscopy, and X-ray crystal structure analysis.     

New Nitrogen,Sulfur-, and Selenium-Donating Ligands Derived from Chiral Pyridine Amino Alcohols. Synthesis and Catalytic Activity in Asymmetric Allylic Alkylation

Although many chiral ligands for asymmetric catalysis have been developed, there is still a need for new structures allowing the modular approach. Recently, easy synthesis of chiral pyridine-containing β-amino alcohols has been elaborated by opening respective epoxides with enantiomeric 1-phenylethylamine. This paper reports the synthetic transformation of β-amino alcohols into the new complexing pyridine-containing seleno- and thioethers. The amino alcohols were effectively converted to cyclic sulfonamidates, which were reacted with thiolates or phenyl selenide nucleophile. The reaction was diastereoselective, and its outcome depended on the configuration at the substitution center. The problem was discussed considering DFT optimized structures of both diastereomeric sulfonamidates. New amino-aldimine ligands were also synthesized from chiral pyridine-containing diamines. Nine new chiral ligands were tested in the Tsuji-Trost allylic alkylation resulting in the enantiomerically enriched product in up to 75% ee. The observed stereochemical induction agrees with the prevailing nucleophilic attack at the allylic carbon laying opposite to the complexing nitrogen of pyridine in η³-allylic intermediate complexes.     

Highly diastereoselective radical addition to glyoxylate imines of chiral amines without additional heteroatoms

The diastereoselective addition of alkyl radicals to glyoxylate imines of α-alkylbenzylamines has been investigated and it was found that diastereoselectivity improved as the size of the alkyl group increased.     

Electrochemical transformations and evaluation of antioxidant activity of some Schiff bases containing ferrocenyl and (thio‐)phenol,catechol fragments

Electrochemical transformations and antioxidant activity of some Schiff bases 1 – 5 containing ferrocenyl group and (thio‐)phenol, catechol fragments were investigated. Compounds under investigation are: 2‐(ferrocenylmethylene)amino)phenol ( 1 ), 2‐((ferrocenylmethylene)amino)‐4,6‐di‐tert‐butylphenol ( 2 ), 2‐((ferrocenylmethylene)amino)‐thiophenol ( 3 ), 3‐((ferrocenylmethylene)hydrazonomethyl)‐4,6‐di‐tert‐butylcatechol ( 4 ) and 2‐((3,5‐di‐tert‐butyl‐4‐hydroxybenzylidene)amino)thiophenol ( 5 ). In a case of compounds 1 – 3 it has shown that the sequence of electrochemical transformations leads to the products of intramolecular cyclization – 2‐ferrocenylbenzoxazole (benzothiazole). o‐Quinone formation occurs during the electrochemical oxidation of catechol‐ferrocene 4 at the first anode stage. Electrochemical oxidation of the redox‐active fragments in Schiff bases 1–4 can be achieved indirectly at a lower potential corresponding to the oxidation of ferrocenyl moiety, consequently these substances can reveal more pronounced antioxidant properties. The antioxidant activities of the compounds were evaluated using 2,2′‐diphenyl‐1‐picrylhydrazyl radical (DPPH) assay, the reaction of 2,2′‐azobis(2‐amidinopropane hydrochloride) (AAPH) induced glutathione depletion (GSH), the oxidative damage of the DNA, the process of lipid peroxidation of rat (Wistar) brain homogenates in vitro. The compounds 1–4 in the antioxidant assays show effectiveness comparable with standard antioxidants (vitamin E, Trolox) and in some parameters superior to them. In the reaction of AAPH with the glutathione compounds 2–5 have a more pronounced protective activity than Trolox. Compounds 1–5 inhibit AAPH induced oxidation damage of the DNA. The more effective inhibitors of the lipid peroxidation process in vitro are molecules containing the bulky tert‐butyl groups: 2 and 4 and Schiff base 3 .     

On the formation of imines in water—a comparison

The reaction of aniline with aryl aldehydes in water has been investigated in the past, but contradictory results have been published. While only small amounts of imines 3 were detected by NMR analysis, isolation afforded high imine yields. A reinvestigation of the reaction of benzaldehyde (1a) and salicylaldehyde (1b) with aniline (2) revealed two important factors which explain the putative contradiction: (i) NMR only reveals the fraction of products which is soluble in water, and (ii) imines 3 form during or after workup.     

Binuclear and polynuclear transition metal complexes with macrocyclic ligands 7. Directed step-by-step synthesis of novel unsymmetric macrocyclic ligands

Novel asymmetric macrocyclic Schiff bases were synthesized by the condensation of N,N′-bis(2-aminophenyl)-3,4-diphenylthiophene-2,5-dicarboxamide (1) with diformyl derivatives of phenol, furan, difurans, pyridine, pyrrole, and dipyrroles. The reaction proceeds in high yields and without by-products in methanol in the presence of inorganic and organic acids (proton-template condensation). In the case of monocyclic diformyl derivatives and di(5-formylfuran-2-yl) sulfide, the reaction occurs in 1,4-dioxane (templateless synthesis). The synthesized macrocycles were characterized by elemental analysis data and NMR and mass spectra. For Part 6, see Ref. 1. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2152–2156, September, 2005.     

手性Schiff碱及其类似物和配合物的研究进展

简要介绍了手性Schiff碱及其类似物和配合物在催化、医药、功能材料中的应用研究进展,为同类课题的进一步研究奠定了基础。     

Carbonyl complexes of manganese, rhenium and molybdenum with 2-pyridylimino acid ligands

[MBr(CO)₃{κ²(N,O)-pyca}] [M = Mn(1a), Re(1b), pyca = pyridine-2-carboxaldehyde] and [MoCl(η³-C₃H₄Me-2)(CO)₂{κ²(N,O)-pyca}] (1c) react with aminoacid β-alanine to give the corresponding iminopyridine complexes 2a-2c. The same method affords the iminopyridine derivatives from γ-aminobutyric acid (GABA) (3a-3c) and 3-aminobenzoic acid (4a-4c). For complexes 2a-2c, 3a, 3c and 4a, the solid state structures have been determined by X-ray crystallography, revealing interesting differences in their hydrogen-bonding patterns in solid state.     

Utilization of 2-substituted 3, 1-benzoxazin-4-ones in synthesis of some quinazoline annulated derivatives

Abstract

In this study, a new series of quinazoline and their annulated derivatives have been synthesized. A number of quiazolinone derivatives substituted at position-3 were prepared from 3, 1-benzoxazinone by the treatment of 3,1-benzoxazinone with different nitrogen nucleophiles such as, hydrazine hydrate, phenylhydrazine, ethanolamine, and cyano acetohydrazide afforded the quinazolinone derivatives 7–11. The reaction of hydrazide derivative 5 with aromatic aldehydes gave the Schiff’s bases derivative 16a–c. Some of the synthesized compounds were tested against the breast cancer cell line (MCF-7). The structures of all the newly synthesized compounds were established based on IR, ¹H, ¹³C NMR, mass spectral data, and elemental analyses.     

Stereoconversion of amino acids and peptides in uryl-pendant binol schiff bases

(S)-2-Hydroxy-2'-(3-phenyluryl-benzyl)-1,1'-binaphthyl-3-carboxaldehyde (1) forms Schiff bases with a wide range of nonderivatized amino acids, including unnatural ones. Multiple hydrogen bonds, including resonance-assisted ones, fix the whole orientation of the imine and provoke structural rigidity around the imine C==N bond. Due to the structural difference and the increase in acidity of the alpha proton of the amino acid, the imine formed with an L-amino acid (1-l-aa) is converted into the imine of the D-amino acid (1-D-aa), with a D/L ratio of more than 10 for most amino acids at equilibrium. N-terminal amino acids in dipeptides are also predominantly epimerized to the D form upon imine formation with 1. Density functional theory calculations show that 1-D-Ala is more stable than 1-L-Ala by 1.64 kcal mol(-1), a value that is in qualitative agreement with the experimental result. Deuterium exchange of the alpha proton of alanine in the imine form was studied by (1)H NMR spectroscopy and the results support a stepwise mechanism in the L-into-D conversion rather than a concerted one; that is, deprotonation and protonation take place in a sequential manner. The deprotonation rate of L-Ala is approximately 16 times faster than that of D-Ala. The protonation step, however, appears to favor L-amino acid production, which prevents a much higher predominance of the D form in the imine. Receptor 1 and the predominantly D-form amino acid can be recovered from the imine by simple extraction under acidic conditions. Hence, 1 is a useful auxiliary to produce D-amino acids of industrial interest by the conversion of naturally occurring L-amino acids or relatively easily obtainable racemic amino acids.     

手性二茂铁类配体在钯催化不对称反应中的应用

本文综述了近10 年来手性二茂铁类配体在钯催化不对称烯丙基取代反应,包括各种不同底物的烯丙基烷基化、烯丙基胺基化和烯丙基磺酰化反应中的应用,并对其在不对称Claisen 重排、不对称Diels-Alder 反应、不对称Heck 反应、不对称羰基化、不对称氢化硅烷化和不对称碳碳键断裂等反应中的应用进行了综述,对部分反应的机理和该领域的发展前景进行了讨论。     

Chiral ferrocene cyanohydrin derivatives—access to novel intermolecularly linked and intramolecularly bridged ferrocene derivatives

By reduction of the cyano group in (R)-(cyanohydroxymethyl)ferrocene and (R,R)-1,1′-bis(cyanohydroxymethyl)ferrocene, amines were obtained giving access to several new diamine and diamide bridged chiral ferrocene derivatives. As a representative for an intramolecularly bridged ferrocene compound bearing two chiral centres (R,R)-8 was obtained with excellent optical purity.     

Synthesis,Characterization, and Crystal Structure of Mononuclear and Dinuclear Dioxomolybdenum(VI) Complexes with Tridentate Schiff‐base Ligands. Part 2

Mononuclear [MoO₂LD], and dinuclear [MoO₂L]₂ or [MoO₂L]₂ · D dixomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff‐base ligands L with [MoO₂(acac)₂]. The Schiff‐base ligands have been synthesized from salicylaldehyde ( 1 , 1a , 1c , 1d ), 2‐hydroxy‐1‐naphthaldehyde ( 2 , 2c ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 3a , 3b , 3c , 3d , 3e ) with 2‐amino‐p‐cresol. All prepared complexes consist of cis‐MoO₂²⁺core coordinated by Schiff‐base ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol, ethanol, dimethyl sulfoxide, imidazole or 4, 4′‐bipyridine). All compounds were characterized by elemental analyses, IR spectroscopy and some of them by X‐ray crystallography ( 1a , 2c , 3a , 3b , 3c and 3e ).     

Synthesis,characterization and anticancer studies of ferrocenyl complexes containing thiazole moiety

A ferrocenyl ligand was prepared from condensation of l,l′‐diacetylferrocene with 2‐amino‐5‐methylthiazole, to give the ligand. This ligand forms 1:1 complexes with lead(II), cobalt(II), nickel(II), copper(II) and zinc(II) in good yield. Characterization of the ligand and complexes was carried out using IR, NMR, electronic absorption, magnetic susceptibility, molar conductivity and elemental analysis. Anticancer activity of the prepared ligand and its complexes against breast cancer cell line MCF‐7 was determined. The anticancer activity of the new complexes was accompanied by significant increase in the activity of superoxide dismutase, with a parallel decrease in the activities of catalase and glutathione peroxidase and reduced glutathione level. Accordingly, the overproduction of free radicals allowed reactive oxygen species‐mediated cancer cell death. The results suggest that the complexes possess significant anticancer activity comparable to cisplatin. Copyright © 2012 John Wiley & Sons, Ltd.