Salicylaldehyde Derivatives Research Articles

ChemInform Abstract: Synthesis of 2,2‐Difluoro‐2H‐chromenes Through the Tandem Reaction of Ethyl 3‐Bromo‐3,3‐difluoropropionate with Salicylaldehyde Derivatives.

Abstract A series of 2,2-difluoro-2H-chromenes were synthesized from the tandem reactions of ethyl 3-bromo-3,3-difluoropropionate with salicylaldehyde derivatives in good yields under basic conditions. In acidic environment defluorination took place during the reaction. A plausible mechanism was proposed based on the experimental results.

Chiral diphenylperhydroindolinol silyl ether catalyzed domino oxa-Michael–aldol condensations for the asymmetric synthesis of benzopyrans

Asymmetric domino oxa-Michael–aldol reactions between trans-cinnamaldehydes and salicylic aldehyde derivatives have been developed. Using (2S,3aS,7aS)-diphenylperhydro indolinol silyl ether 4i as the catalyst, most corresponding chiral benzopyrans can be obtained with excellent chemo- and enantioselectivities.

Mononuclear and dinuclear salen type copper(II) Schiff base complexes: Synthesis, characterization, crystal structures and catalytic epoxidation of cyclooctene

A series of salen type Schiff base ligands and their mononuclear (CuLn, n=1–4) or dinuclear Cu(II) complexes (Cu2(L5)2) were synthesized and characterized by 1H NMR, IR and UV–Vis spectroscopy as well as elemental analyses. The ligands were synthesized from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with various salicylaldehyde derivatives (x-salicylaldehyde for H2Ln, x=H (n=1), 5-Br (n=2), 5-Br-3-NO2 (n=3), 3-OMe, (n=5)) and 2′-hydroxyacetophenone (n=4). Crystal structures of two complexes (CuL4 and Cu2(L5)2) were determined. Catalytic performance of the complexes was studied in the epoxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxidant. Various factors including reaction temperature, solvent type, time, catalyst amount and substrate to oxidant ratio were optimized. High catalytic activity and epoxides selectivity was found. Solvent free epoxidation of cyclooctene was also studied and higher catalytic activity, epoxide selectivity and lower reaction times were observed.

Azomethines based on O-phosphorylated derivatives of salicylaldehyde and orto-/para-aminophenols

In recent years azomethines derived from Salicylaldehyde and aminophenols and their metal complexes attract increasing interest of researchers. Some of these compounds possess high antimicrobial, antibacterial, tuberculocidal, and antioxidant activities [1–6], catalyze the olefins epoxidation [7] and inhibit steel corrosion [8]. In view of the above, their derivatives containing thiophosphoryl group instead of hydroxy group may be promising tridentate ligands. Synthesis of Schiff bases of this type was carried out by reacting salicylaldehyde thiophosphorylated derivatives with orthoand para-aminophenols. Compounds Ia and Ib were obtained via reaction of salicylaldehyde with diphenylchlorothiophosphinate and 2-chloro-2-thioxo-5,5-dimethyl-1,3,2-dioxaphosphorinane [9] in the presence of a base. DOI: 10.1134/S1070363214020352

Screening of a library of hemisalen ligands in asymmetric H-transfer: Reduction of aromatic ketones in water

A library of chiral hemisalen ligands (30) was realized. The ligands were synthesized by the condensation of salicylaldehyde derivatives with amino-alcohols (amino-indanol or substituted amino-ethanol) and characterized. These ligands associated with ruthenium (II) precursors were tested on the asymmetric transfer hydrogenation (ATH) of aromatic ketones by sodium formate in water. The different substituent pattern on the ligand (electronic and hindrance effects on different positions) as well as the ruthenium precursor were investigated. The best compromise in terms of conversion and chiral induction led to the complex [RuCl2(mesitylene)]2 coordinated to (1S,2R)-1-((E)-(3-(dimethyl(phenyl)silyl)-2-hydroxy-5-methoxy benzylidene) amino)-2,3-dihydro-1H-inden-2-ol (L25). It reduces acetophenone in 95% yield and 91% ee in 18 h at 30°C. © 2013 Academie des sciences.

Synthesis, crystal structures and antibacterial studies of oxidovanadium(IV) complexes of salen-type Schiff base ligands derived from meso-1,2-diphenyl-1,2-ethylenediamine

A series of new derivatives and previously reported Schiff base ligands and their oxidovanadium(IV) complexes were synthesized, characterized and tested as potential antibacterial agents against four human pathogenic bacteria. These N2O2 type Schiff base ligands were derived from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with different salicylaldehyde derivatives, and their metal complexes were obtained from the reaction of these ligands with bis(acetylacetonato)oxidovanadium(IV). Our studies showed that the metal complexes had moderate antibacterial activity, and this activity was higher than that of the free ligands against both Gram-positive and Gram-negative bacteria. Besides, it was found that the presence of more substituents on the ligands increases the antibacterial activities of both the free ligands and their complexes. The crystal structures of H2L4 and its corresponding complex VOL4 were determined by X-ray crystallography.

Adsorption Properties of Modified Banana Fiber to Transition Metal Ions

Several syntheses of metal ion adsorbents using modified banana fibers having Schiff bases were investigated. In addition, adsorption properties of a metal ion adsorbent were also evaluated. Alkalitreated (BF)-g-(glycidyl methacrylate)(BF-GMA) were synthesized. The Schiff base, 2-2'{iminobis[ethane-2,1-diylnitrilo(E)methylidine]}bisphenol derivative was synthesized by the reaction of diethylenetriamine and salicylaldehyde derivatives in methanol. The metal ion adsorbents were synthesized by the reaction of 2,2'-{iminobis-[ethane-2,1-diylnitrilo(E)methylidine]}bisphenol derivative, and BF-GMA. Where, C1: R=H, C2: R=Cl, C3: R=Br. The concentration of metal ion was measured by an inductively coupled plasma atomic emission spectroscope. Metal ion adsorption percentage (%) of BFGMA(C3) was higher than those of BF-GMA(C1) and BF-GMA(C2). Especially, adsorption property to Co2+ was higher than that to the other metal ions. This result suggests that the acid dissociation constant of BF-GMA(C3) is larger than that of BF-GMA(C1). Therefore, BF-GMA(C3) can be chelated with metal ions more easily than BF-GMA(C1) can be. These results show a definite feasibility of the use of banana fibers for the metal ion adsorbent.

Subcomponent self-assembly of polymer chains based on dynamic and geometrical coordination diversity of the first row transition metal ions

The subcomponent self-assembly of polymer chains based on the dynamic/geometrical coordination diversity of first row transition metal ions is reported. A well-defined NH2-functional hydrophilic block copolymer, Ni(II), Cu(II) and Zn(II) and a salicylaldehyde derivative are selected as subcomponents. The imine formation and self-assembly are followed using 1H NMR, DLS, GPC, and UV-vis spectroscopy. The results demonstrate that the subcomponent self-assembly strongly depends on the coordination stability constants and geometries of these metal ions. Ni(II) induces interchain coordination, and rapid phase transition to macro-phase separation but with the lowest autocatalysis efficiency. However, Cu(II) ions induce intrachain coordination with the most remarkable autocatalysis, and the delaying of the phase transition to form well-defined hybrid nanoparticles. The behaviour with Zn(II) ions is in between that with Ni(II) and Cu(II) ions. This striking differentiation demonstrates that the dynamic/geometrical coordination diversity of the abundant first row transition metal ions effectively control the subcomponent self-assembly of polymer chains, and thus the hierarchical nanostructures of dative metal–polymer hybrid functional materials.

2,2′-(Hydrazine-1,2-diylidenedimethylylidene)bis(6-isopropyl-3-methylphenol) based selective dual-channel chemosensor for Cu2+ in semi-aqueous media

A novel receptor based on a substituted salicylaldehyde derivative, 2,2′-(hydrazine-1,2-diylidenedimethylylidene)bis(6-isopropyl-3-methylphenol) (1), was synthesized and characterized using various spectroscopic techniques.

Synthesis, spectral, electrochemical and catalytic properties of Ru(III) Schiff base complexes containing N, O donors

A series of new hexa coordinated ruthenium(III) complexes of the type [RuY2(EPh3)2(X-DPMP)] (where Y=Br or Cl; E=P or As; DPMP=2-[(2,6-Diisopropyl-phenylimino)-methyl]-phenol, X=H, Br, Cl, I and Ph) have been synthesized by equimolar [RuY3(EPh3)3] and the Schiff base ligands in benzene. The bidentate Schiff base ligands (X-DPMP) have been derived from condensation of 2,6-diisopropylaniline with mono and multisubstituted salicylaldehyde derivatives. The complexes have been characterized by elemental analysis, magnetic susceptibility, UV–Vis., IR and EPR spectral and electrochemical measurements. All the ruthenium(III) complexes are found to be stable, paramagnetic, low spin, redox active and display either quasi reversible or irreversible redox couples based on metal centre. They have exhibited catalytic activity for the oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant.

Nanoplatforms attached Schiff bases by condensation method; Investigation of glucose oxidase enzyme as biocatalysts

We report a easy approach for the immobilization of glucose oxidase enzyme (GOx) on nanoparticles. Nanoparticles-modified polystyrene-ANH2 (PSA) with some salicylaldehyde derivatives were synthesized by means of condensation and investigated the enzymatic properties of GOx immobilized on there. Modified polystyrenes were characterized using IR spectra, gel permeation chromatography, and scanning electron microscopy. All the characteristics of the immobilized glucose oxidase (PSA-SalH)-GOx, (PSA-SalCH3)-GOx, and (PSA)-GOx enzyme showed except one of them. Immobilized GOx on to (PSA) showed two optimum pH, other immobilized polymers were one optimum.

Synthesis of 2,2-difluoro-2H-chromenes through the tandem reaction of ethyl 3-bromo-3,3-difluoropropionate with salicylaldehyde derivatives

A series of 2,2-difluoro-2H-chromenes were synthesized from the tandem reactions of ethyl 3-bromo-3,3-difluoropropionate with salicylaldehyde derivatives in good yields under basic conditions. In acidic environment defluorination took place during the reaction. A plausible mechanism was proposed based on the experimental results.

Mo(IV) and W(IV) cyanido complexes with Schiff bases. Synthesis, X-ray single crystal structures, physicochemical properties and quantum chemical calculations

In the reaction of salicylaldehyde derivatives and aminoethanol with Mo(IV) or W(IV) cyanido complexes, six new salts were isolated and characterized by physicochemical measurements. The single crystal X-ray analysis of four salts of the formula (PPh4)2[M(CN)3O(LL)]·nH2O, (where LL=Schiff bases formed in situ in the reaction of aminoethanol and 5-bromo-, 5-chloro-, 5-methoxy-, 3,5-dichloro- or 5-bromo-3-methoxy-substituted salicylaldehyde, M=Mo or W, n=1, 1.5, 2 or 5 water molecules) reveals a distorted octahedral geometry of the anions. All the complexes were characterized by elemental analysis, IR and UV–Vis spectroscopy and by cyclic voltammetry measurements. The role of the salicylaldehyde substituents on the structures and physicochemical properties is discussed. The results are compared with quantum chemical calculations, indicating that, contrary to literature data, even strong hydrogen bonds do not influence the anion structure.

Electronic and steric effects of substituents in series of Zn2+ asymmetrical bis-Schiff-base ligands complexes on catalytic ring-opening copolymerization of CHO and MA

Based on the half-unit Schiff-base ligand HL and series of asymmetrical bis-Schiff-base ligand H2Ln (n = 1–6) in situ synthesized from the reaction of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), o-phenylenediamine, and/or different salicylaldehyde derivatives, complexes [Zn(L)2] (1) and series of [Zn(Ln)] (n = 1–6, 2–7) are obtained, respectively. Complex 1 proves to be inactive, resulting from its saturated octahedral coordination environment around the central Zn2+ ion, while in complexes 2–7, the unsaturated coordination environment for the catalytic active centers (Zn2+ ions) permits the monomer insertion for the effective bulk or solution copolymerization of CHO (cyclohexene oxide) and MA (maleic anhydride). As to the electron and steric effect in complexes 2–7 on the catalytic behaviors, the copolymerization results show that the introduction of withdrawing –Br substituent para to the phenoxide group endows higher reactive activity, while the bulkiness effect of the encumbering substituent (–Br, –OMe or tert-butyl) ortho to the phenoxide groups is in favor of the chain growth of the copolymers. Moreover, all the bulk copolymerizations in 2-7/DMAP (4-(dimethylamino)pyridine) systems afford poly(ester-co-ether)s, while lower catalyst and co-catalyst concentration for 3/DMAP system is helpful for the formation of perfectly alternating polyester in solution. Of the three co-catalysts, DMAP is found to be the most efficient, while an excess thereof is detrimental for the chain growth of the copolymers.

Greener construction of 4H-chromenes based dyes in deep eutectic solvent

Green solvents such as deep eutectic solvents are new emerging alternatives to the conventional harmful organic solvents which may find a number of interesting applications in industrial and chemical processes. A facile, atom-economic and environmentally-benign one-pot reaction of salicylaldehyde and malononitrile with various nucleophiles, including indoles, thiols, secondary amines, cyanide and azide were efficiently achieved in choline chloride based deep eutectic solvent (DES). Products distribution of the current green protocol depend on the nature of the nucleophile used in the reaction. The one-pot reaction of salicylaldehyde derivatives and malononitrile with thiols, indoles, and cyanide give 2-amino-3-cyano-4H-chromene derivatives. Secondary amines result in the formation of benzopyrano[2,3-d] pyrimidines, due to the further reaction of salicylaldehyde with 4H-chromene under the same reaction condition. The DES was recycled without any reduction in activity or yield. Therefore, the synthesis of chromene based dyes in green solvents at room temperature under catalyst-free conditions is a promising alternative to previously used procedures.

One‐Pot Enantioselective Synthesis of 3‐Nitro‐2H‐chromenes Catalyzed by a Simple 4‐Hydroxyprolinamide with 4‐Nitrophenol as Cocatalyst

AbstractThe asymmetric domino oxa‐Michael–Henry reaction of salicylaldehyde derivatives with trans‐β‐nitro olefins catalyzed by a readily available trans‐4‐hydroxy‐L‐prolinamide with 4‐nitrophenol as an effective cocatalyst is presented. The corresponding 3‐nitro‐2H‐chromenes were obtained in moderate to excellent yields (up to 99 %) and with up to 90 % ee under mild conditions. In addition, a preliminary study shows that this organocatalytic system is able to promote the domino aza‐Michael–Henry reaction of 2‐formylpyrrole derivatives with trans‐β‐nitro olefins to give chiral 2‐nitro‐3H‐pyrrolizines.

PH-sensitive fluorescent salicylaldehyde derivative for selective imaging of hydrogen sulfide in living cells

The salicylaldehyde derivative, 9-formyl-8-hydroxyjulolidine was developed as a fluorescent probe to detect weak acid ions. With the salicylaldehyde moiety as the chromophore, the probe exhibits pH sensitive detection of hydrogen sulfide and silicate in aqueous solution. It displays an excellent selectivity for hydrogen sulfide and silicate over other weak acid salts. Time-dependent density functional theory calculations confirmed that the fluorescence turn-on mechanism involved blocking intramolecular charge transfer. The probe detects S2− in live cells, providing a powerful method to study H2S chemistry in biological systems.

Spectroscopic Studies of Amino Acid Ionic Liquid-Supported Schiff Bases

Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (l-threonine, l-valine, l-leucine, l-isoleucine and l-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on 13C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the l-histidine derivative) a proton transfer equilibrium exists and the presence of the COO− group stabilizes the proton transferred NH-form.

Calixarene and hemicarcerand-like compounds obtained by self-assembly of 3-aminophenylboronic acid and salicylaldehyde derivatives

One-pot synthesis of calixarene and hemicarcerand like compounds can be modulated by use of mono- or bis-salicylaldehyde derivatives respectively, reacting with 3-aminophenylboronic acid. Thus, the first part of this work is focused on the synthesis of calix-like compounds derived from salicylaldehyde units including different substituents on the aromatic moiety. Seven different calix structures are described and their structural analysis has been carried out by spectroscopic techniques. The second part corresponds to the description of bis-salicylaldehyde derivatives, synthesis and reactivity towards the 3-aminophenylboronic acid leading to the formation of hemicarcerand-like compounds. Aliphatic and aromatic chains were inserted as linkers between the two salicylaldehyde units in order to evaluate the influence on the formation of the hemicarcerands compounds. Both, calixarene and hemicarcerand compounds resulted from condensation reactions, wherein the formation of N–B coordination bonds plays a significant role on the macrocyclization process.

SYNTHESIS AND ANTIOXIDANT ACTIVITIES OF [5-FLUORO N, N’-BIS (SALICYLIDENE) ETHYLENEDIAMINE] AND [3, 5-FLUORO N, N’-BIS (SALICYLIDENE) ETHYLENEDIAMINE] MANGANESE (III) COMPLEXES

Antioxidants act as free radical scavengers in the oxidation processes. Thus, they will certainly play diverse roles in the biological systems and the therapy of a wide variety of diseases. Regarding this fact, in the present study, we synthesized two new salen ligand compounds by the condensation of ethylendiamine and salicylaldehyde derivatives in excellent yields. The structures of these ligands were confirmed by IR, 1 H NMR and mass spectroscopy techniques. Furthermore, we evaluated the relative dismutase, catalase and peroxidase activities of the newly synthesized complexes named as EUKs 131, 132, 141 and 142 relative to EUKs 108 and 8, as the reference compounds. The results demonstrated that all Mn-salen complexes (EUKs) illustrated significant dismutase, catalase and peroxidase activities. EUKs 131 and 8 showed the most catalase and peroxidase activities while their dismutase activities were almost the same as the other compounds. In addition, our data indicated that the biological activities of the EUKs are modulated by manganese element as well as the types and the positions of substituents on the ligand.