Search results for "Thiosemicarbazones"
showing 7 items of 7 documents
Revisiting the thiosemicarbazonecopper(II) reaction with glutathione. Activity against colorectal carcinoma cell lines.
2018
Thiosemicarbazones (TSCs), and their copper derivatives, have been extensively studied mainly due to the potential applications as antitumor compounds. A part of the biological activity of the TSC-CuII complexes rests on their reactivity against cell reductants, as glutathione (GSH). The present paper describes the structure of the [Cu(PTSC)(ONO2)]n compound (1) (HPTSC =pyridine-2-carbaldehyde thiosemicarbazone) and its spectroscopic and magnetic properties. ESI studies performed on the reaction of GSH with 1 and the analogous [{Cu (PTSC*)(ONO2)}2] derivative (2, HPTSC* =pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) show the absence of peaks related with TSC-Cu-GSH species. However GS…
Regio- and Stereoselective Synthesis of Spiropyrrolizidines and Piperazines through Azomethine Ylide Cycloaddition Reaction.
2015
A series of original spiropyrrolizidine derivatives has been prepared by a one-pot three-component [3 + 2] cycloaddition reaction of (E)-3-arylidene-1-phenyl-pyrrolidine-2,5-diones, l-proline, and the cyclic ketones 1H-indole-2,3-dione (isatin), indenoquinoxaline-11-one and acenaphthenequinone. We disclose an unprecedented isomerization of some spiroadducts leading to a new family of spirooxindolepyrrolizidines. Furthermore, these cycloadducts underwent retro-1,3-dipolar cycloaddition yielding unexpected regioisomers. Upon treatment of the dipolarophiles with in situ generated azomethine ylides from l-proline or acenaphthenequinone, formation of spiroadducts and unusual polycyclic fused pip…
A DFT study of [3 + 2] cycloaddition reactions of an azomethine imine with N-vinyl pyrrole and N-vinyl tetrahydroindole
2016
The mechanism and selectivities of the [3+2] cycloaddition (32CA) reactions of azomethine imine (AI) 8 with two N-vinyl five-membered heterocycles (NVFH), 9a and 9b, have been theoretically studied using DFT methods at the MPWB1K/6-31G(d) computational level. The possible ortho/meta regio- and endo/exo stereoselective channels were explored and characterised. The low polar character of these 32CA reactions, which is the consequence of the high nucleophilic character of both reagents, as well as the non-effective reactivity of these NVFH as nucleophiles, accounts for the high calculated activation energies, 16.1 (9a) and 16.8 (9b) kcalmol-1 in chlorobenzene. Analysis of the relative electron…
A Molecular Electron Density Theory Study of the Reactivity of Azomethine Imine in [3+2] Cycloaddition Reactions
2017
The electronic structure and the participation of the simplest azomethine imine (AI) in [3+2] cycloaddition (32CA) reactions have been analysed within the Molecular Electron Density Theory (MEDT) using DFT calculations at the MPWB1K/6-311G(d) level. Electron localisation function (ELF) topological analysis reveals that AI has a pseudoradical structure, while the conceptual DFT reactivity indices characterise this TAC as a moderate electrophile and a good nucleophile. The non-polar 32CA reaction of AI with ethylene takes place through a one-step mechanism with low activation energy, 5.3 kcal/mol-1. A bonding evolution theory (BET) study indicates that this reaction takes place through a non-…
Structure, magnetic properties and nuclease activity of pyridine-2-carbaldehyde thiosemicarbazonecopper(II) complexes.
2008
New complexes of formulae [Cu(HL 2 )(H 2 O)(NO 3 )](NO 3 ) ( 1 ), [{Cu(L 1 )(tfa)} 2 ] ( 2 ), [{Cu(L 1 )} 2 (pz)](ClO 4 ) 2 ( 3 ) and {[{Cu(L 1 )} 2 (dca)](ClO 4 )} n ( 4 ), where HL 1 = pyridine-2-carbaldehyde thiosemicarbazone, HL 2 = pyridine-2-carbaldehyde 4 N -methylthiosemicarbazone, Htfa = trifluoroacetic acid (CF 3 COOH), pz = pyrazine (C 4 H 4 N 2 ) and dca = dicyanamide [N(CN) 2 ] − , have been synthesized and characterized. The crystal structures of these compounds are built up of monomers ( 1 ), dinuclear entities with the metal centers bridged through the non-thiosemicarbazone coligand ( 2 and 3 ) and 1D chains of dimers ( 4 ). In all the cases, square–pyramidal copper(II) io…
Oxidative cyclization of aldehyde thiosemicarbazones induced by potassium ferricyanide and by tris(p-bromophenyl)amino hexachloroantimoniate. A joint…
2005
The oxidative ring closure reaction of some aryl-substituted thiosemicarbazones induced by "bona fide" one-electron abstracting agents was investigated, by means of both experimental and computational techniques. The corresponding 1,2,4-triazole derivatives were the only cyclization products observed. The occurrence of two slightly different mechanistic pathways for the reaction is discussed.
A competitive reactivity study on the oxidative cyclization of thiosemicarbazones into 1,3,4-thiadiazoles
2022
Abstract In order to obtain useful insights on the mechanism of formation of 2(3H)-imino-1,3,4-thiadiazoles by oxidative cyclization of aldehyde thiosemicarbazones with Cu(II) or Fe(III) salts, a competitive reactivity study was performed on a suitable set of diversely substituted substrates, by means of HPLC techniques. This approach enabled to exploit Hammett’s equation without performing otherwise difficult-to-run kinetic experiments. The results presented herein support the hypothesis that the formation of the thiadiazole ring is induced by the attack of the oxidizing Lewis acid metal cation onto the imine-like nitrogen atom of the thiosemicarbazone substrate. Beyond mechanistic interpr…