Schiff base insertion in titanium alkyls; reduction of imine functions by benzyl addition

1999 ◽  
Vol 77 (12) ◽  
pp. 2095-2098 ◽  
Author(s):  
Simon J Coles ◽  
Michael B Hursthouse ◽  
David G Kelly ◽  
Andrew J Toner ◽  
Neil M Walker

TiBz4 reacts with N-2-fluorenyl(salicylideneimine) to afford a crystallographically characterized titanium(IV) complex containing two conventional bidentate Schiff base ligands and two O-bound ligands in which the imine function has been reduced by the addition of benzyl and hydrogen moieties.Key words: insertion, nucleophilic additions, Schiff bases, titanium

2016 ◽  
Vol 81 (10) ◽  
pp. 1111-1119 ◽  
Author(s):  
Fatemeh Bagheri ◽  
Abolfazl Olyaei

A novel method was developed for synthesizing a series of new three dentate Schiff base ligands starting from hydroxynaphthalidene pyrimidinyl amines with o-phenylenediamines or o-aminophenol or 2-amino-3-hydroxy-pyri-dine in the presence of formic acid catalyst under solvent-free conditions. In these reactions [1+1] condensation product as half-unit ligand was obtained. Moreover, the reaction of hydroxynaphthalidene pyrimidinyl amines with 3,4-diamino-pyridine and 1,8-naphthalenediamine lead to the formation of C2-naphthylated imidazopyridine and dihydropyrimidine, respectively. The attractive features of this protocol are: use of inexpensive catalyst, operationally simple, short reaction times, easy handling, and good yields.


2018 ◽  
Vol 42 (6) ◽  
pp. 4646-4652 ◽  
Author(s):  
Hua Zhang ◽  
Junyang Xing ◽  
Yanhong Dong ◽  
Shangqing Xie ◽  
Shishuai Ren ◽  
...  

The sp2 C–H bond activation of the HCN moiety in diphenylphosphino benzalimines was realized using CoMe(PMe3)4 with the elimination of methane.


2019 ◽  
Vol 48 (33) ◽  
pp. 12496-12511 ◽  
Author(s):  
G. Kalaiarasi ◽  
S. Dharani ◽  
V. M. Lynch ◽  
R. Prabhakaran

Three tetranuclear (1–3) complexes and a mononuclear (4) palladium(ii) complex were synthesized from 3-acetyl-chromen-2-one Schiff base ligands [H2-3MAC-Rtsc] (where R = H; CH3; C2H5[H2-3MAC-etsc] or C6H5) and potassium tetrachloropalladate.


1988 ◽  
Vol 43 (5) ◽  
pp. 611-615 ◽  
Author(s):  
T. Sogo ◽  
J. Romero ◽  
A. Sousa ◽  
A. de Blas ◽  
M. L. Durán ◽  
...  

Abstract The electrochemical synthesis and physico-chemical properties of neutral zinc(II) complexes of bidentate Schiff bases derived from salicylaldehydes are presented together with the X-ray structure of bis[N-(4-methylphenyl)salicylaldiminato]zinc(II). The crystal is monoclinic, a = 21.877(3), b = 8.801(2), c = 12.027(5) Å, β = 96.55(3)°, space group C2/c. The complex is a monomer, and the zinc atom is tetrahedrally coordinated.


1973 ◽  
Vol 26 (7) ◽  
pp. 1459 ◽  
Author(s):  
WW Fee ◽  
JD Pulsford ◽  
PD Vowles

The kinetics of copper(II)-promoted solvolyses of two series of nickel(II) complexes containing polydentate Schiff bases with various remote substituents, in dimethyl sulphoxide (dmso), are discussed from the viewpoints of rate constants and of enthalpies and entropies of activation. Appearance of an isokinetic relation for the tridentate (ONS donors) reactants may indicate a common mechanism operative within this reactant series. Rate constants appear related to σp values in such a way that a dissociative mechanism appears important for the tridentate reactants, while characterization in terms of associative behaviour is indicated for the tetradentates.


2010 ◽  
Vol 75 (8) ◽  
pp. 1075-1084 ◽  
Author(s):  
Muhammad Imran ◽  
Mitu Liviu ◽  
Shoomaila Latif ◽  
Zaid Mahmood ◽  
Imtiaz Naimat ◽  
...  

The condensation reactions of biacetyl with orthohydroxyaniline and 2-aminobenzoic acid to form bidendate NO donor Schiff bases were studied. The prepared Schiff base ligands were further utilized for the formation of metal chelates having the general formula [ML2.2H2O] where M = Co(II), Ni(II), Cu(II) and Zn(II) and L = HL1 and HL2. These new compounds were characterized by conductance measurements, magnetic susceptibility measurements, elemental analysis, and IR, 1H-NMR and electronic spectroscopy. Both Schiff base ligands were found to have a mono-anionic bidentate nature and octahedral geometry was assigned to all metal complexes. All the complexes contained coordinated water which was lost at 141-160 ?C. These compounds were also screened for their in-vitro antibacterial activity against four bacterial species, namely; Escherichia coli, Staphylococcus aureus, Salmonella typhi and Bacillus subtillis. The metal complexes were found to have greater antibacterial activity than the uncomplexed Schiff base ligands.


2015 ◽  
Vol 35 (4) ◽  
pp. 191-224 ◽  
Author(s):  
Ikechukwu P. Ejidike ◽  
Peter A. Ajibade

AbstractThe huge research on Schiff base coordination complexes in the past few decades has given rise to several new molecules that have been of biological importance. The ease with which the Schiff base ligands are designed and prepared and their pattern is elucidated have made them to be referred to as “fortunate ligands” possessing azomethine derivatives, the C=N linkage that is essential for biological activity, including antibacterial, antifungal, antioxidant, anticancer, and diuretic activities. A variety of Schiff base and its complexes have been studied as model molecules for biological oxygen carrier systems. The uses of Schiff bases as DNA-cleaving agents and its mode of interaction and free-radical scavenging properties are described. The review encapsulates the applications of Schiff bases and their complexes.


2020 ◽  
Vol 21 (2) ◽  
pp. 555 ◽  
Author(s):  
Sokratis T. Tsantis ◽  
Demetrios I. Tzimopoulos ◽  
Malgorzata Holynska ◽  
Spyros P. Perlepes

Even 155 years after their first synthesis, Schiff bases continue to surprise inorganic chemists. Schiff-base ligands have played a major role in the development of modern coordination chemistry because of their relevance to a number of interdisciplinary research fields. The chemistry, properties and applications of transition metal and lanthanoid complexes with Schiff-base ligands are now quite mature. On the contrary, the coordination chemistry of Schiff bases with actinoid (5f-metal) ions is an emerging area, and impressive research discoveries have appeared in the last 10 years or so. The chemistry of actinoid ions continues to attract the intense interest of many inorganic groups around the world. Important scientific challenges are the understanding the basic chemistry associated with handling and recycling of nuclear materials; investigating the redox properties of these elements and the formation of complexes with unusual metal oxidation states; discovering materials for the recovery of trans-{UVIO2}2+ from the oceans; elucidating and manipulating actinoid-element multiple bonds; discovering methods to carry out multi-electron reactions; and improving the 5f-metal ions’ potential for activation of small molecules. The study of 5f-metal complexes with Schiff-base ligands is a currently “hot” topic for a variety of reasons, including issues of synthetic inorganic chemistry, metalosupramolecular chemistry, homogeneous catalysis, separation strategies for nuclear fuel processing and nuclear waste management, bioinorganic and environmental chemistry, materials chemistry and theoretical chemistry. This almost-comprehensive review, covers aspects of synthetic chemistry, reactivity and the properties of dinuclear and oligonuclear actinoid complexes based on Schiff-base ligands. Our work focuses on the significant advances that have occurred since 2000, with special attention on recent developments. The review is divided into eight sections (chapters). After an introductory section describing the organization of the scientific information, Sections 2 and 3 deal with general information about Schiff bases and their coordination chemistry, and the chemistry of actinoids, respectively. Section 4 highlights the relevance of Schiff bases to actinoid chemistry. Sections 5–7 are the “main menu” of the scientific meal of this review. The discussion is arranged according the actinoid (only for Np, Th and U are Schiff-base complexes known). Sections 5 and 7 are further arranged into parts according to the oxidation states of Np and U, respectively, because the coordination chemistry of these metals is very much dependent on their oxidation state. In Section 8, some concluding comments are presented and a brief prognosis for the future is attempted.


2004 ◽  
Vol 82 (9) ◽  
pp. 1346-1352 ◽  
Author(s):  
Diane A Dickie ◽  
Hanifa Jalali ◽  
Rahul G Samant ◽  
Michael C Jennings ◽  
Jason AC Clyburne

2,4,6-Triphenylbenzaldehyde 1 undergoes a condensation reaction with 2-aminophenol to give N-(2′,4′,6′-triphenylbenzylidene)-2-iminophenol (TPIP) 2. The imine 2 can be reduced with NaBH4 in ethanol to form N-(2′,4′,6′-triphenylbenzyl)-2-aminophenol (TPAP) 3. Addition of trimethylaluminum to 2 or 3 results in the formation of the complexes TPIP-AlMe2·AlMe3 (4) or TPAP-AlMe2 (5). Compounds 2, 3, and 4 have been crystallographically characterized.Key words: N,O ligands, aluminum, m-terphenyl, Schiff bases, X-ray crystallography.


2016 ◽  
Author(s):  
Elżbieta Hejchman ◽  
Barbara Sowirka ◽  
Magdalena Tomczyk ◽  
Dorota Maciejewska

Based on World Health Organization (WHO) report, it was estimated that one in five people before age 75 will suffer from cancer during their lifetime, and more than 13 million cancers death will happen in 2030. Chemotherapy is a basic approach for the treatment of cancer diseases. However, because of drug resistance and considerable side effects drug-induced toxicity, the discovery of new metal analogs with promising activity and high therapeutic index is an urgent need. The fundamental role of copper and the recognition of its complexes as important bioactive compounds in vitro and in vivo aroused an ever-increasing interest in these agents as potential drugs for therapeutic intervention in various diseases. Schiff bases are a critical class of compounds in medical chemistry that have demonstrated significant chemotherapeutic and antibacterial application. Schiff base Cu(II) complexes revealed great potential for antiproliferative, antibacterial, and gastroprotective activity. Coumarins are a wide class of natural and synthetic compounds that showed diverse pharmacological activities including anticancer activity. Among the wide variety of coumarins, 7-hydroxycoumarin derivatives have been shown to possess desirable antiproliferative activities. In particular, their antibacterial, antifungal and anticancer activities make the compounds attractive for further derivatization and screening as novel therapeutic agents. Taking these compounds as lead, we have designed and synthesized a series of new copper(II) complexes with coumarin-derived Schiff base ligands. Two series of Schiff bases were prepared by condensation of 8-formyl-7-hydroxy-4-methylcoumarin and 8-acetyl-7-hydroxy-4-methylcoumarin with p-substituted aniline derivatives. These compounds were used as ligands in the synthesis of copper(II) complexes. The obtained Schiff bases as well as copper complexes are mostly novel molecules. Only the products of condensation 8-formyl-7-hydroxy-4-methylcoumarin with p-toluidine and 8-acetyl-7-hydroxy-4-methylcoumarin with p-toluidine and its copper(II) complex were synthesized, but the anticancer activity of these compounds was not determined. The assay of their cytotoxic activity is in progress. Preliminary, we have identified two copper(II) coordination compounds of 7-hydroxy-8-[1-(4-methoxyphenyl imino)ethyl]-4-methyl-2H-chromen-2-one and 7-hydroxy-8-[1-(4-hydroxyphenyloimino)ethyl]-4-methyl-2H- chromen-2-one having dose-dependent antiproliferative activity on HeLa cancer cell line. Additionally, the Schiff bases – derivatives of substituted salicylaldehydes and 2-hydroxyacetophenones condensed with appropriate anilines were prepared. Such compounds have been reported in scientific papers, their copper complexes have not been assayed yet, and may serve as an useful tool in QSAR investigation.


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