- New water soluble bis-imidazolium salts with a saldach scaffold: Synthesis, characterization and in vitro cytotoxicity/bactericidal studies
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A series of water-soluble bis-imidazolium salts of the type H 2(iPr)2saldach(1,2-Me2Im +-X-)2 (4) and their mononuclear complexes [M(III)Cl{(iPr)2saldach(1,2-Me2Im +-X-)2}] (M = Mn, 5; Fe, 6), (X = Cl, a; PF6, b; BF4, c), where saldach = N,N′- bis(salicylidene)-(±)-trans-1,2-diaminocyclohexane, have been synthesized and characterized using elemental analysis, electronic, spectral, magnetic as well as conductometric methods and MALDI-TOF-, ESI-MS. All complexes possess a distorted square pyramidal coordination geometry with MN2O 2Cl chromophore, as revealed by the elemental, spectral and literature data. These salts have been evaluated for in vitro cytotoxicity against HepG-2 and MCF-7 cell lines. Among them, 4c (IC50 = 22.17 μM) exhibited potency against MCF-7. The bactericidal efficacy of 4a-c was screened against a panel of common pathogenic bacteria. Compound 4a was found to be the most potent antibacterial agent and could inhibit all the bacterial strains more effectively than standard antibiotics.
- Elshaarawy, Reda F.M.,Kheiralla, Zeinab H.,Rushdy, Abeer A.,Janiak, Christoph
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- Co-delivery of imidazolium Zn(II)salen and Origanum Syriacum essential oil by shrimp chitosan nanoparticles for antimicrobial applications
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This study reports preparation and physicochemical characterization of natural antimicrobials (Origanum Syriacum essential oil (OSEO), shrimp chitosan nanoparticles (CSNPs)) and new imidazolium ionic liquid-supported Zn(II)Salen. These antimicrobials were
- Hassan, Yasser A.,Khedr, Amgad I.M.,Alkabli,Elshaarawy, Reda F.M.,Nasr, Ali M.
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- UHMWPE with short-chain branches synthesized by alkenyl substituted phenoxy–imine catalysts in ethylene polymerization
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The alkenyl substituted phenoxy–imine complexes [2-C3H5-6-(2, 3, 5, 6-C6F4H-N?CH)C6H3O]2TiCl2 (C3H5=?CH2? CH?CH2 or ?CH?CH?
- Wang, Yi,Fan, Hong,Li, Bo-Geng
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Read Online
- 67Ga-metalloprobes: monitoring the impact of geometrical isomers on accumulation profiles in rat cardiomyoblasts and human breast carcinoma cells
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Geometrically similar monocationic gallium(iii) complexes and their radiolabeled SPECT counterparts were obtained from Schiff base precursor ligands using ligand exchange reactions to evaluate the impact of cis and trans-isomers on their cellular accumula
- Sivapackiam, Jothilingam,Harpstrite, Scott E.,Rath, Nigam P.,Sharma, Vijay
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supporting information
p. 158 - 161
(2017/02/05)
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- Ionic Sal-SG Schiff bases as new synergetic chemotherapeutic candidates: Synthesis, metalation with Pd(ii) and in vitro pharmacological evaluation
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A series of novel N-(salicylidene)-sulfaguanidines (Sal-SG) bearing ionic liquid (IL) terminals (ILSSGH, 4a-f) have been synthesized by Schiff base condensation of IL-functionalized salicylaldehydes (ILSal, 3a-g) and sulfaguanidine (SG). Metalation trials of these ionic Schiff bases with palladium(ii) chloride affords the corresponding Pd(ii) complexes, [Pd(ii)(ILSSG)Cl(H2O)] (5a-g). Further, the antimicrobial profiles of the new compounds against a set of common pathogens have been described. Zone of inhibition (ZOI) and minimal inhibitory concentration (MIC) values revealed that most of the new compounds exhibited significant antibacterial and potential inhibitory activity against Staphylococcus aureus (S. aureus), and this activity is modulated by substituents attached to the ionic liquid core as well as the counter-ion.
- Elshaarawy, Reda F. M.,Mostafa, Tahia B.,Refaee, Ayaat A.,El-Sawi, Emtithal A.
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p. 68260 - 68269
(2015/09/01)
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- Iron(iii)-salan complexes catalysed highly enantioselective fluorination and hydroxylation of β-keto esters and N-Boc oxindoles
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Chiral iron(iii)-salan complexes catalysed highly enantioselective α-fluorination and α-hydroxylation of β-keto esters and N-Boc oxindoles to give the corresponding products in high yields and good-to-excellent ee values under mild reaction conditions. This journal is the Partner Organisations 2014.
- Gu, Xin,Zhang, Yan,Xu, Zhen-Jiang,Che, Chi-Ming
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supporting information
p. 7870 - 7873
(2014/07/08)
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- Asymmetric induction via short-lived chiral enolates with a chiral C-O axis
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A novel method has been developed for the asymmetric cyclization of alkyl aryl ethers. The reactions were assumed to proceed via short-lived chiral enolate intermediates with a chiral C-O axis to give cyclic ethers with tetrasubstituted carbon in up to 99% ee. The half-life of racemization of the chiral enolate intermediate was roughly estimated to be ~1 s at -78 C.
- Yoshimura, Tomoyuki,Tomohara, Keisuke,Kawabata, Takeo
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supporting information
p. 7102 - 7105
(2013/06/27)
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- Enantioselective intramolecular formal [2 + 4] annulation of acrylates and α,β-unsaturated imines catalyzed by amino acid derived phosphines
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The first chiral phosphine-catalyzed activation of acrylates for intramolecular formal [2 + 4] reactions with unsaturated imines is described. The catalytic reactions afford N-heterocycles with exceptionally high diastereo- and enantioselectivities. The [2 + 4] products are amenable for further transformations to useful molecules such as chiral piperidines and multicyclic structures.
- Jin, Zhichao,Yang, Ruojie,Du, Yu,Tiwari, Bhoopendra,Ganguly, Rakesh,Chi, Yonggui Robin
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supporting information; experimental part
p. 3226 - 3229
(2012/08/08)
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- Large ultra-high molecular weight polyethylene spherical particles produced by AlR3 activated half-sandwich chromium(iii) catalysts
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A series of half-sandwich pentamethylcyclopentadienyl chromium(iii) complexes bearing a salicylaldiminato ligand, Cp*[2-R1-4-R 2-6-(CHNR3)C6H2O]CrCl [R1 = iPr (1, 4), tBu (2, 3, 5), Ad (6); R2 = H (1, 2, 3), tBu (4, 5, 6); R3 = iPr (1, 2, 5, 6), tBu (3, 4)], were synthesized. All complexes were characterized by elemental analyses and the structures of complexes 1-4 and 6 were determined by X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlR3, complexes 1-6 all catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with a diameter of 1-6 mm. The catalytic activity of these complexes and the molecular weight of the produced polyethylene can be tuned in a broad range by changing the R1, R 2, and R3 groups as well as the AlR3 cocatalyst. It was found that complex 6 with R1 = Ad, R2 = tBu, and R3 = iPr shows the highest catalytic activity and produces polyethylene with the highest molecular weight. The Royal Society of Chemistry 2011.
- Sun, Mingtai,Xu, Tieqi,Gao, Wei,Liu, Yang,Wu, Qiaolin,Mu, Ying,Ye, Ling
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experimental part
p. 10184 - 10194
(2011/12/05)
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- Expeditious synthesis of benzopyrans via lewis acid-catalyzed C-H functionalization: Remarkable enhancement of reactivity by an ortho substituent
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An expeditious construction of a benzopyran skeleton via Lewis acid-catalyzed C-H functionalization was achieved. In this process, a [1,5] hydride shift and 6-endo cyclization successively occurred to give benzopyrans. The presence of substituents ortho to the alkoxy group significantly enhanced the reactivity, affording the desired compounds in excellent chemical yields with short reaction times.
- Mori, Keiji,Kawasaki, Taro,Sueoka, Shosaku,Akiyama, Takahiko
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supporting information; experimental part
p. 1732 - 1735
(2010/09/05)
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- ANALOGS OF PROPOFOL, PREPARATION THEREOF AND USE AS ANESTHETICS
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Compounds of formula (I) wherein X is H or F and pharmaceutically acceptable salts thereof are useful as anesthetics.
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- Asymmetric Henry reaction catalyzed by a copper tridentate chiral schiff-base complex
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A series of copper-tridentate chiral Schiff-base complexes were prepared and employed in an asymmetric Henry reaction, affording the corresponding adducts in good yields and with high enantioselectivities (up to 96% ee).
- Lai, Guoyin,Wang, Sujing,Wang, Zhiyong
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p. 1813 - 1819
(2008/12/22)
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- Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
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Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
- Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
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p. 4433 - 4451
(2008/02/09)
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- Synthesis of substituted salicylamines and dihydro-2H-1,3-benzoxazines
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Phenols were converted to their magnesium salts with the MgCl2-Et3N base system and subsequently reacted with Eschenmoser's salt, affording N,N-dimethyl substituted benzylamines in high to excellent yields. A series of mono N-substituted benzylamines were prepared in one-pot syntheses by ortho-formylation of phenols to corresponding salicylaldehydes, which in turn reacted with amines to imines. The imines were subsequently reduced to mono N-substituted benzylamines. Some of these benzylamines were further converted, without work-up, to mono N-substituted dihydro-2H-1,3-benzoxazines.
- Anwar, Hany F.,Skatteb?l, Lars,Hansen, Trond Vidar
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p. 9997 - 10002
(2008/02/13)
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- Synthesis of allyl-terminated syndiotactic polypropylene: Macromonomers for the synthesis of branched polyolefins
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Low molecular weight syndiotactic polypropylene (syndio-PP) with an olefin end group was synthesized using methylaluminoxane-activated bis(phenoxyimine)titanium dichloride ((PHI)2TiCl2) catalysts. Propylene enchainment occurs by a 2,
- Cherian, Anna E.,Lobkovsky, Emil B.,Coates, Geoffrey W.
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p. 6259 - 6268
(2008/02/02)
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- 1,2-AZOLE DERIVATIVES WITH HYPOGLYCEMIC AND HYPOLIPIDEMIC ACTIVITY
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A compound represented by the formula (1) wherein ring A is a ring optionally having 1 to 3 substituents; ring B is a 1,2-azole ring which may further have 1 to 3 substituents; Xa, Xb and Xc are the same or different and each is a bond, - O -, - S - and the like; Ya is a divalent aliphatic hydrocarbon residue having 1 to 20 carbon atoms; Yb and Yc are the same or different and each is a bond or a divalent aliphatic hydrocarbon residue having 1 to 20 carbon atoms; ring C is a monocyclic aromatic ring which may further have 1 to 3 substituents; and R represents -OR4 (R4 is hydrogen atom or optionally substituted hydrocarbon group) and the like, or a salt thereof or a prodrug thereof is useful as an agent for the prophylaxis or treatment of diabetes and the like.
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- Biaryl-bridged Schiff base complexes of zirconium alkyls: Synthesis structure and stability
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Three substituted salicylaldimine derivatives H2 L1-3 of 2,2′-diamino-6,6′-dimethylbiphenyl give, under appropriate conditions, isolable alkyls of zirconium [ZrL1-3R2] (R=CH2Ph, CH2 But). Two molecular structures confirm their cis-α geometry (C2-symmetric with cis alkyl ligands). They decompose via 1,2-migratory insertion of an alkyl group to imine, followed in some instances by a second similar reaction. The dimeric molecular structure of one such doubly-inserted product is presented. The kinetics of decomposition by this process are studied briefly, and it is noted that the rate increases with increased steric demand of the salicylaldimine unit.
- Knight, Paul D.,O'Shaughnessy, Paul N.,Munslow, Ian J.,Kimberley, Brian S.,Scott, Peter
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p. 103 - 113
(2007/10/03)
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- Syndiospecific living propylene polymerization catalyzed by titanium complexes having fluorine-containing phenoxy-imine chelate ligands
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The propylene polymerization behavior of a series of Ti complexes featuring fluorine-containing phenoxy-imine chelate ligands is reported. The Ti complexes combined with methylalumoxane (MAO) can be catalysts for living and, at the same time, stereospecific polymerization of propylene at room temperature or above. DFT calculations suggest that the attractive interaction between a fluorine ortho to the imine nitrogen and a β-hydrogen of a growing polymer chain is responsible for the achievement of room-temperature living propylene polymerization. Although the Ti complexes possess C2 symmetry, they are capable of producing highly syndiotactic polypropylenes. 13C NMR is used to demonstrate that the syndiotacticity is governed by a chain-end control mechanism and that the polymerization is initiated exclusively via 1,2-insertion followed by 2,1-insertion as the principal mode of polymerization. 13C NMR spectroscopy also elucidated that the polypropylenes produced with the Ti complexes possess regio-block structures. Substitutions on the phenoxy-imine ligands have profound effects on catalytic behavior of the Ti complexes. The steric bulk of the substituent ortho to the phenoxy oxygen plays a decisive role in achieving high syndioselectivity for the chain-end controlled polymerization. Over a temperature range of 0-50 °C, Ti complex having a trimethylsilyl group ortho to the phenoxy oxygen forms highly syndiotactic, nearly monodisperse polypropylenes (94-90% rr) with extremely high peak melting temperatures (Tm = 156- 149 °C). The polymerization behavior of the Ti complexes can be explained well by the recently proposed site-inversion mechanism for the formation of syndiotactic polypropylene by a Ti complex having a pair of fluorine-containing phenoxy-imine ligands.
- Mitani, Makoto,Furuyama, Rieko,Mohri, Jun-ichi,Saito, Junji,Ishii, Seiichi,Terao, Hiroshi,Nakano, Takashi,Tanaka, Hidetsugu,Fujita, Terunori
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p. 4293 - 4305
(2007/10/03)
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- A family of zirconium complexes having two phenoxy - imine chelate ligands for olefin polymerization
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A zirconium complex having two phenoxy - imine chelate ligands, bis[N-(3-tert-butylsalicylidene)-anilinato]zirconium(IV)dichloride (1), was found to display a very high ethylene polymerization activity of 550 kg of polymer/mmol of cat·h with a viscosity average molecular weight, (Mv) value of 0.9 × 104 at 25 °C at atmospheric pressure using methylalumoxane (MAO) as a cocatalyst. This activity is 1 order of magnitude larger than that exhibited by Cp2ZrCl2 under the same polymerization conditions. The use of Ph3CB(C6F5)4/i-Bu3Al in place of MAO as a cocatalyst resulted in extremely high molecular weight polyethylene, Mv 505 × 104, with an activity of 11 kg of polymer/mmol of cat·h at 50 °C. This Mv value is one of the highest values displayed by homogeneous olefin polymerization catalysts. Complex 1, using Ph3CB(C6F5)4/i-BU3Al as a cocatalyst, provided a high molecular weight ethylene-propylene copolymer, Mv 109 × 104, with 8 kg of polymer/mmol of cat·h activity at a propylene content of 20.7 mol %. X-ray analysis revealed that complex 1 adopts a distorted octahedral coordination structure around the zirconium metal and that two oxygen atoms are situated in trans position while two nitrogen atoms and two chlorine atoms are situated in cis position. DFT calculations suggest that the active species derived from complex 1 possesses two available cis-located sites for efficient ethylene polymerization. Changing the tert-butyl group in the phenoxy benzene ring enhanced the polymerization activity. Bis[N-(3-cumyl-5-methylsalicylidene)cyclohexylaminato]zirconium(IV)dichloride (7) with MAO displayed an ethylene polymerization activity of 4315 kg of polymer/mmol of cat·h at 25 °C at atmospheric pressure. This activity corresponds to a catalyst turnover frequency (TOF) value of 42 900/s· atm. This TOF value is one of the largest not only for olefin polymerization but also for any known catalytic reaction. Ligands with additional steric congestion near the polymerization reaction center gave increased Mv values. The maximum Mv value, 220 × 104 using MAO, was obtained with bis[N-(3,5-dicumylsalicylidene)-2′-isopropylanilinato]zirconium (IV)dichloride (15). Thus, polyethylenes ranging from low to exceptionally high molecular weights can be obtained from these zirconium complexes by changing the ligand structure and the choice of cocatalyst.
- Matsui,Mitani,Saito,Tohi,Makio,Matsukawa,Takagi,Tsuru,Nitabaru,Nakano,Tanaka,Kashiwa,Fujita
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p. 6847 - 6856
(2007/10/03)
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- Investigation of Mn(III)-based oxidative free radical cyclization reactions toward the synthesis of triptolide: The effects of lanthanide triflates and substituents on stereoselectivity
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Mn(III)-mediated oxidative free radical cyclization reactions are useful for construction of polycyclic compounds. In the total synthesis of triptolide (3) and its related compounds, construction of tricyclic skeletons 4 and 5 was achieved by the Mn(OAc)
- Yang, Dan,Ye, Xiang-Yang,Xu, Ming,Pang, Kwan-Wah,Cheung, Kung-Kai
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p. 1658 - 1663
(2007/10/03)
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- Prodrugs: Part 3. 2-Formylphenyl esters of indomethacin, ketoprofen and ibuprofen and 6-substituted 2-formyl and 2-acylphenyl esters of aspirin
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The synthesis and study of a novel series of potential prodrugs of indomethacin, ketoprofen, ibuprofen and aspirin are reported. 2-Formylphenyl esters of the NSAIDs, together with two 6-substituted 2-formyl and two 2-acylphenyl aspirins and 4-formylphenyl indomethacin, have been prepared. A study of their alkaline and neutral hydrolysis shows that these compounds, with the exception of 2-acetylphenyl aspirin, act as true prodrugs of the NSAIDs, giving the NSAID and acylphenol. The rates of hydrolysis and activation parameters indicate that the 2-acylphenyl esters employ an intramolecular catalytic route. The 2-formylphenyl esters were more potent as anti-inflammatory agents than the parent compounds in the carragheenan-induced paw oedema test.
- Abordo, Evelyn A.,Bowden, Keith,Huntington, Anthony P.,Powell, Sarah L.
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- Substituted 2H-benzoxazin-2-ones
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A new class of N-alkyl or N-alkenyl, 2,3-dihydro--4-thioxo-2H-1,3-benzoxazin-2-ones is disclosed. This class of compounds is useful in the control of plant pests. Thus, pesticidal compositions comprising these benzoxazin-2-ones with a carrier therefor are
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- Selective Reactions between Phenols and Formaldehyde. A Novel Route to Salicylaldehydes
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Treatment of phenols (1) with 2 mol equiv. of paraformaldehyde in aprotic and poorly electron-donating solvents in the presence of selected metal halides coupled with suitable bases produces salicylaldehydes (3) in high yields.The route is highly selective for ortho-formylation and also specific towards monoformylation.The crucial role of added bases is emphasized.
- Casiraghi, Giovanni,Casnati, Giuseppe,Puglia, Giuseppe,Sartori, Giovanni,Terenghi, Giuliana
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p. 1862 - 1865
(2007/10/02)
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