Texte remanié de: Thèse--Sc. phys.--Perpignan, 1972. N°: 1281. / Extrait du "Bulletin de la Société chimique de France" N°4, 1971, pp. 1336-1343. Conservé sous la cote: [4° THS. Pièce. 513].

Dans le cadre de nos travaux, nous avons développés des voies de synthèses permettant d'accéder à deux familles d'hétérocycles aromatiques: les phosphonylpyrazoles, et les fluoropyridazines. La synthèse des pyrazoles phosphonylés a été réalisée en utilisant un couplage croisé pallado-catalysé de type Hirao, et nous avons démontré qu'un système catalytique unique à base de Pd(OAc)2/XantPhos pouvait catalyser le couplage entre une large gamme d'halogénopyrazoles et de H-phosphonyles. Bien que souffrant de certaines limites dans son champ d'application, notamment au niveau du motif de substitution de l'halogénopyrazole, cette méthode consiste probablement à l'heure actuelle la voie d'accès la plus modulable pour accéder aux pyrazoles phosphonylés.Les 5-fluoropyridazines ont été synthétisées par réactions de cycloadditions séquentielles [2+1]/[3+2] entres des alcynes, le difluorocarbène :CF2, et des diazoacétates d'alkyles. Nous avons démontré que cette séquence réactionnelle était compatible avec un grand nombre d'alcynes diversement substitués, et que les 5-fluoropyridazines ainsi obtenues pouvaient être aisément fonctionnalisées. / The work presented in this manuscript concerns the development of synthetic routes to two families of heterocycles, namely phosphonylpyrazoles and fluoropyridazines. Phosphonylpyrazoles were synthesized using a Hirao-type cross-coupling, and it was demonstrated during this study that a single catalytic system based on Pd(OAc)2/XantPhos could perform the cross-coupling between a wide range of halopyrazoles and H-phosphonyls. Significant limits have been met in the scope of this method, especially regarding the substitution pattern of the halopyrazole. Nevertheless, at this time, this method is arguably one of the most flexible ways to synthesize phosphonylpyrazoles. Fluoropyridazines were synthesized using a [2+1]/[3+2] cycloaddition sequence between alkynes, the difluorocarbene :CF2, and alkyl diazoacetates. It was demonstrated during this study that a wide range of alkynes could be involved in this sequence, and that the corresponding 5-fluoropyridazines could be easily diversified.

No description available.

Scorpionates are versatile and flexible ligands with a wide range of applications including catalysis, C-H bond activation, formation of new class of materials, and mimicking enzymatic reactions. This is as a result of its steric and electronic properties, and due to the relative ease with which the 3, and 5-positions of the pyrazole ring can be functionalized. In this work, we report the synthesis of a new class of scorpionate ligands known as cyanoscorpionates which can crosslink various metal centers. Thus, bis (4-cyano-3,5-diphenylpyrazolyl)borate BpPh2,4CN was synthesized and fully characterized by 1H NMR and FT-IR. Coordination of bis (4-cyano-3,5-diphenylpyrazolyl)borate BpPh2,4CN to thallium (I) metal was performed and characterized and we are looking to elucidating its molecular structure by X-ray crystallography in future.

Four main series of novel heterocyclic compounds were successfully syniliesised. Two of these series were found to be post-emergence herbicides with the activities of each being based on a different mode of action. The (pyrazole-4-yl)alkanones are inhibitors of protoporphyrinogen oxidase, an enzyme in chlorophyll biosynthesis, whereas alkyl 3-arylsulfonylamino- 3-methyllhio-2-(pyrimidin-2-ylcarbamoyl)acrylates and pyrimidin-2-yl 3-(2- chlorophenyl)sulfonyl-amino-3-methylthio-2-cyanoacrylamides (collectively termed "vinylogous sulfonylureas") are inhibitors of acetohydroxy acid synthase (AHAS). an enzyme in branched-chain amino acid biosynthesis. Both these enzymes are established targets for current commercial herbicides. Studies of the utility of 2-(l-ethoxyalkylidene)-3-oxoaIkanenitriles (acrylonilriles) in heterocycle synthesis were facilitated by the recent development of a convenient route to these starting materials. Acrytonitriles were reacted with different hydrazines to give (pyrazol-4-yl)alkanones and pyrazole-4-carbonitriles in varying proportions depending on the reaction conditions and the substituents on the reactants. Although distinction between alternative 3- and 5-substituted pyrazoles is a perennial problem in pyrazole synthesis, in this case the products of these reactions were successfully characterised and identified using a range of n.m.r. spectroscopy techniques. Once the herbicidal mode of action of the (pyrazol-4-yl)alkanones had been confirmed, synthesis of a series of analogues allowed the structural elements contributing to biological activity to be identified. The reaction of acrylonitriles with bidetate nucleophiles such as thiourea gave novel pyrimidines. but these compounds were not herbicidal. The vinylogous sulfonylureas were synthesised using established procedures to obtain novel compounds structurally related to the commercial herbicide chlorsulfuron. The biological activity of the vinylogous sulfonylureas was found to be sensitive to apparently minor changes in structure, but x-ray crystallographically-generated structures of an active and an inactive member of the series revealed marked differences in conformation. Some of the vinylogous sulfonylureas were used as synthons for pyrazole and pyrazolopyrimidine derivatives. Although these compounds did not exhibit herbicidal activity, this synthesis provided the basis for some interesting chemistry. Unexpected elimination of the arylsulfonylamino group was observed when a vinylogous sulfonyurea was treated with methyl hydrazine. In order to confirm the identity of the 3-methylthiopyrazole product, model compounds were synthesised using alternative routes. The resulting pairs of 3- and 5-substituted pyrazoles were characterised using n.m.r spectroscopy.

This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallurgy processes for separating and concentrating metals in laterite ores and describes new flowsheets proposed by Anglo American. Chapter 2 considers whether single reagent molecules with sets of tridentate donor atoms can generate sufficiently stable nickel(II) complexes to allow selective extraction of nickel from an aqueous sulfate solution. The salicylaldimines, 3-X-4-alkyl-6-(quinolin-8-imino)phenol, 3-X-4-alkyl-6-(2- methoxyphenylimino)phenol and 3-X-4-alkyl-6-(2-thiomethoxyphenylimino)phenol (alkyl = tert-butyl or tert-octyl; X = H, Br or NO2), were selected for study. The synthesis and characterisation of these proligands and their nickel(II) complexes are reported. XRD structures of Br-substituted salicylaldimines and their nickel(II) complexes are compared and discussed. The 4-tert-octylsalicylaldimines were used to extract nickel(II) from an aqueous sulfate solution with a pH > 2.8 and 3- nitro-4-tert-octyl-6-(quinolin-8-imino)phenol was found to be the strongest extractant in the series with a pH0.5 of 3.5. Computational studies of an analogous series of salicylaldimine proligands in the gas phase calculated the formation energies of their nickel(II) complexes and the predicted trend follows the experimentally determined solvent extraction results. Chapter 3 investigates modifications to phenolic pyrazoles, which are known copper(II) extractants. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)-phenols (X = H, OMe, Br and NO2) was synthesised and characterised. Varying the 6-X-substituent of the phenolic pyrazole altered the strength of copper extraction and 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)-1H-pyrazol-3-yl)-phenol was found to be the strongest extractant in the series. Analysis of XRD structures of related phenolic pyrazoles and their copper(II) complexes showed evidence of inter- and intra-molecular hydrogen bonding. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. The double deprotonation of 4-tert-butyl-(pyrazol-3-yl)-phenol at high pH forms a polynuclear complex in the organic phase with a copper(II) to ligand ratio of 1:1, thereby increasing the mass transport efficiency of copper by the reagent. The synthesis and characterisation of the [Cu16(4-tert-butyl-(pyrazol-3-yl)- phenolate)16(EtOH)4(H2O)2] wheel complex was carried out to demonstrate how such polynuclear copper(II) complexes could be formed under solvent extraction conditions. Chapter 4 explores the solvent extraction of nickel(II) and cobalt(II) by novel combinations of neutral nitrogen-donor heterocyclic ligands with organic acids, such as dinonylnaphthelenesulfonic acid (DNNSAH). The synthesis and characterisation of 2,6-bis(5-alkyl-1H-pyrazol-3-yl)-pyridine, 2-(5- alkyl-1H-pyrazol-3-yl)-pyridine and 5,5'-alkyl-3,3'-bi-1H-pyrazole (alkyl = tert-butyl or nonyl) and their nickel(II) complexes were reported. Also reported are synthesis and 6-N-alkyl-2-(2-pyridinyl)- benzothiazole (alkyl = n-butyl or n-decyl) and 2-(1-Isopropyl-benzimidazol-2-yl)-pyridine. The extraction of nickel(II) from highly acidic mixed metal aqueous sulfate solutions by some of these ligands was studied. These synergistic mixtures demonstrated remarkable strength and selectivity for nickel(II), and cobalt(II) over iron(II). XRD structures of nickel(II) complexes of 2,6-bis(5-tert-butyl- 1H-pyrazol-3-yl)-pyridine, 2-(5-tert-butyl-1H-pyrazol-3-yl)-pyridine and 5,5'-tert-butyl-3,3'-bi-1Hpyrazole with sulfonates or perchlorates as ion-pairs have intermolecular hydrogen bonding interactions between the inner-sphere ligands and the counterions.

Pyrazoles have been focus of a large number of investigations in the design and synthesis of novel biologically active agents that show remarkable medicinal activities. Although pyrazoles have been studied for over a century as an important class of heterocyclic compounds, they still continue to attract considerable attention due to the wide range of medicinal activities they possess. Recent studies have shown that combination of a ferrocenyl unit with structural features of pyrazoles can lead to products with enhanced or/and unexpected biological activity since several ferrocene derivatives have already been shown to be active against a number of tumors. As a result, we have investigated the reaction of 3-ferrocenylpropynal with hydrazinium salts. As anticipated, these reactions afforded two kinds of pyrazoles, namely 1-alkyl/aryl-5-ferrocenylpyrazoles (1,5-isomer) and 1-alkyl/aryl-3- ferrocenylpyrazoles (1,3-isomer). In most cases, 1,5-pyrazole isomers have resulted from these reactions as the single or the major product of the reactions. The structures of 1-benzyl-5-ferrocenylpyrazole, 1-phenyl-5-ferrocenyl-pyrazole and 1- (2-hydroxy-ethyl)-3-ferrocenylpyrazole were identified by X-ray single crystal analysis. The analogous reactions between 3-phenylpropynal and hydrazinium salts were also studied, which afforded 1-alkyl/aryl-5-phenylpyrazoles (1,5-isomer) and/or v 1-alkyl/aryl-3-phenylpyrazoles (1,3-isomer). The regioselectivity of the reactions is mainly governed by the nature of the substituents in hydrazine derivative.

Pyrazoles have been intensely studied in the design and synthesis of biologically active agents because they display considerable medicinal activities. Recent studies have shown that integration of a ferrocenyl unit with structural features of pyrazoles can result in the formation of the new products with enhanced or/and unexpected biological activity since several ferrocene derivatives have already been illustrated to be active against a number of tumors. Therefore, we have investigated the electrophilic cyclizations of the hydrazones to afford 5-ferrocenyl-4-((4-nitrophenyl)sulfenyl)-substituted pyrazole derivatives. First, the requisite hydrazone derivatives were synthesized by the reactions of ferrocenyl propargyl aldehydes or ketones with a series of hydrazines. Then electrophilic cyclizations of these hydrazones were investigated by treating with 4-(nitrophenyl)sulfenyl chloride as electrophile. By employing these electrophilic cyclizations, a series of 5-ferrocenyl-4-((4-nitrophenyl)sulfenyl)-1H-pyrazoles, 5-ferrocenyl-4-((4-nitrophenyl) sulfenyl)-3-methyl-1H-pyrazoles and 5-ferrocenyl-4-((4-nitrophenyl)sulfenyl)-3-phenyl-1H-pyrazoles have been synthesized in moderate to good yields.

No description available.

No description available.