This thesis reports on the feasibility of the utilization of organotin hydrides as enaantioselective free radical reducing agents. The chiral organotin hydrides prepared contain the bulky chiral (1R,2S,5R)-menthyl substituent and in some cases also contain a stereogenic tin centre. Reaction of (1R,2S,5R)-menthylmagnesium chloride (MenMgC1) with triphenyltin chloride in THF proceeds with epimerization of the C-1 carbon of the menthyl group and results in a mixture of (1R,2S,5R)-menthyltriphenyltin and (1S,2S.5R)-menthyltriphenyltin. Addition of Lewis bases such as triphenylphosphine to the THF solution of triphenyltin chloride prior to the addition of the Grignard reagent suppresses epimerization and enables isolation of pure (1R,2S,5R)-menthyltriphenyltin. (1R,2S,5R)-Menthyltriphenyltin is the precursor for the synthesis of (1R,2S,5R)-menthyldiphenyltin hydride as well as (1R,2S,5R)-menthyl-containing organotin halide derivatives. A crystal structure of (1R,2S,5R)-menthylphenyltin dibromide and (1R,2S,5R)-menthylphenyltin dichloride confirmed the configuration of the menthyl substituent in these compounds. Reaction of MenMgC1 with diphenyltin dichloride in THF proceeds with no epimerization of the C-1 carbon of the menthyl group and bis((1R,2S,5R)-menthyl)diphenyltin is formed. A crystal structure of (1R,2S,5R)-menthyltriphenyltin confirmed the configuration of the menthyl substituent. Bis((1R,2S,5R)-menthyl)diphenyltin is used to form bis((1R,2S,5R)-menthyl)phenyltin hydride as well as other bis(1R,2S,5R)-menthyl derivatives. A series of chiral non-racemic triorganotin halides and triorganotin hydrides containing one or two (1R,2S,5R)-menthyl substituents as well as various potentially intramolecular coordination substituents were synthesized and characterized. The intramolecular substituents include the 8-(dimethylamino)naphthyl, 2-[(1S)-1-dimethylaminoethyl]phenyl, 2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl and the 2-(4-(S)isopropyl-2-oxazoline)-5-methylphenyl substituents. Each compound containing a stereogenic tin centre was synthesized as diastereomeric mixtures. AM1 calculations of these compounds provide good qualitative predictability of the molecular geometries observed in the solid state as well as the diastereomeric ratios observed in solution. X-ray analysis of some of the organotin halides containing intramolecular coordination substituents revealed a tendency towards penta-coordination at the tin centre as a result of N-Sn interactions. The chiral organotin hydrides synthesized were found to be poor enantioselective free radical reducing agents. However, the addition of one molar equivalent of achiral or chiral Lewis acids to the free radical reduction reactions involving these organotin hydrides results in remarkable increases in enantioselectivity. There are numerous examples in which enantioselectivities exceed 80% and three examples of enantioselectivites which are equal and above 90% with one outstanding enantioselective outcome of ≥99%. These results appear to be the highest enantioselectivites for organotin hydride radical reductions reported to date. There is strong evidence to suggest that the chiral menthyl group of the organotin hydride directs the stereochemical outcome in the reduced product. The results also suggest that an increase in the number of menthyl substituents attached to tin or the introduction of intramolecular coordination substituents does not necessarily results in a greater increase in enantioselectivity. Preliminary studies into the synthesis of organotin hydrides containing Lewis acid functionalities are also reported. A zirconium chloride functionality was found to be incompatible with organotin hydride. However, an organotin hydride containing a trialkylboron Lewis acid functionality attached via an alkyl chain was successfully synthesized. Although this reagent was only stable in the preparative THF solution, it was still found to be effective at reducing benzaldehyde to benzyl alcohol.

A series of 2,6- and 3,5-ethynylpyridyl compounds and their cobalt clusters have been prepared and analysed in Chapter 2, in order to study through-space and through-bond interactions between the ethynyl arms. Bidentate N- donor ligands, such as bipyridine and o-phenanthroline with alkyne functionality have been used extensively as building blocks for a wide range of molecular materials, but monodentate ethynylpyridyls have received less attention. The results showed that while there is no orbital restriction on a RC[triple bond]C-n-[pi]�cc-C[triple bond]CR through-bond interaction in 2,6-ethynylpyridyls, no significant interaction exists. Nevertheless, there are intramolecular interactions as manifested in the distortions which occur in the solid state structure of the compounds and the lability of the diphenylphosphine methane (dppm) moieties in the oxidised Co₂(CO)₄dppm species. Polymerisation by Sonogashira coupling between dibromo pyridines or diiodo ferrocene and ethynyl pyridines resulted in only oligomeric fractions that could be separated. The thesis also reports the synthesis and characterization of some novel naphthalimide monomers with acrylic and allyl headgroups. The naphthalimide moiety is substituted in the 4-position with various functionalities. This is presented in detail in Chapter 3 of the thesis. The monomers� structure is the following: [illustration omitted] wherein: A may be a polymerizable group (methacrylate or allyl), which includes a spacer entity (aliphatic or aromatic); B is selected from an ethenyl or ethynyl linked organometallic group, a halogen and/or an amine (i.e. bromo, ethynylferrocene, ethenylferrocene, trimethylsilylethynyl, nitro, piperidine and ethenylpiperidine). The acrylic monomers were synthesized by coupling 4-bromo-1,8-naphthalic anhydride with an amino alcohol to give an imide, which then was coupled with methacryloyl chloride to provide the methacrylate. Functionalization in the 4-position of the naphthalimide moieties was achieved by Sonogashira and Heck coupling reactions with for example ethynylferrocene, trimethylsilyl acetylene, vinylferrocene. For the allyl monomers synthesis, a reaction between allyl amine and 4-Bromo-naphthalic anhydride provided 4-bromo-naphthalimido allyl, which was then functionalized by further Sonogashira and Heck coupling reactions. The monomers were polymerised and copolymerised with other widely used comonomers, such as methyl methacrylate, methyl acrylate, styrene, vinyl carbazole and acrylonitrile. The polymerisation processes and the full analyses of the (co)polymers are described in Chapter 4. Free radical polymerisation, FRP, initiated by azo bisisobutyronitrile, AIBN at elevated temperature was the main technique employed for making the (co)polymers. Atom Transfer Radical Polymerisation, ATRP was conducted for some monomers although the results were inconclusive (the yields were low, under 50%, but the molecular weight distributions were quite narrow, PDI�s <1.7). Heck coupling polymerisation was performed for the bromo- substituted methacrylic and allyl monomers and supplied colorful, well-defined polymeric materials, with low polymerisation degrees. All polymers were analyzed by HPLC, NMR, UV-VIS, IR, electrochemistry and fluorescence. The (co)polymers made by FRP had various molecular masses (Mn = 3000- 90.000), whereas the polydispersities were PDI = 1.4- 4.6. Most of the (co)polymers were fluorescent and had good thermal and electrochemical properties. Potential applications of the polymers have been suggested and relevant literature background in the field is provided in both Chapters 1 and 4. The monomers/ polymers are stable compounds (no special storage conditions required) and can act as good candidates for potential applications in light emitting devices, as resins/ binders for coating materials, in the dyes and pigment industry and also for manufacturing of conducting polymers and/or composite materials.

Aquesta Tesi Doctoral s'ha basat en el disseny de materials moleculars nanoporosos i magnètics. En aquest sentit, s'ha dissenyat una nova estratègia sintètica enfocada a l'obtenció de materials híbrids metal·lorgànics que combinin canals de grans dimensions i propietats magnètiques interessants. Fins aleshores, el disseny d'un material d'aquestes característiques presentava certes contradiccions sintètiques, fet que provocava que la seva síntesi resultés molt complicada. No obstant, la introducció, per part del nostre grup, d'una variació consistent en l'ús de lligands amb caràcter paramagnètic ha permès obtenir diversos materials amb ambdues característiques.Un primer material molecular nanoporós i amb ordenament magnètic (designat com a MOROF-1, metal-organic radical open-framework) s'ha sintetitzat utilitzant un ió metàl·lic com el coure(II) i un radical perclorotrifenilmetílic trifuncionalitzat amb tres grups carboxílics (D. MASPOCH, NATURE MATERIALS, 2002, 2, 190). Aquest compost presenta unes característiques nanoporoses realment interessants. Les dimensions dels seus canals són d'aproximadament 3 nm. A més, la desorpció i absorció de molècules de dissolvent (etanol o metanol) provoca uns canvis estructurals sorprenents: el materials té un comportament semblant al d'una esponja molecular; conferint-li unes bones característiques per poder actuar com a sensor de dissolvents com el metanol i etanol. A més, aquesta estructura altament porosa s'ordena ferromagnèticament a baixes temperatures. Aquest material també ha vingut acompanyat de dos nous materials, tots ells amb interessants propietats poroses i magnètiques. El material MOROF-2 (D. MASPOCH ET AL., CHEM COMMUN., 2004, 1164) es defineix com un sòlid paramagnètic amb una topologia arquitectònica inèdita fins ara i amb uns canals helicoidals. Altrament, el material MOROF-3 novament s'ordena magnèticament i també presenta una porositat important.Per altra banda, l'ús d'aquest radicals com a blocs moleculars paramagnètics enllaçats per ponts d'hidrogen també ha permès l'obtenció dels primers materials moleculars purament orgànics porosos i magnètics, els quals són estables en absència de dissolvent pressenten una estabilitat tèrmica elevada (275º©). Aicí, l'empaquetament del radical PTMDC forma un material molecular paramagnètic (POROF-1) amb una estructura composta d'uns nanocontenidors moleculars hidrofòbics de fins a 1 nm de diàmetre connectats a través de finestres hidrofíliques de 5 Å (D. MASPOCH ET AL., J. AM. CHEM. SOC., 2004, 126, 730) . D'altra banda, el radical PTMTC forma un segon material purament orgànic porós (POROF-2), el qual s'ordena magnèticament (D. MASPOCH, ANGEW. CHEM. INT. ED., 2004, 43, 1828).S'ha demostrat doncs la viabilitat de l'ús d'aquests nous materials moleculars porosos i magnètics com a materials de partida per la formació de materials moleculars multifuncionals. Aplicant aquesta aproximació, s'ha aconseguit sintetitzar un materials molecular porós que combina canals formats per parets amb diversos grups quirals i propietats magnètiques d'interès. / This thesis has mainly focused on the design of nanoporous and magnetic molecular materials. In this way, in our group, we have designed a new synthetic strategy for the obtaining of hybrid metal-organic materials that could combine large nanopores and interesting magnetic properties. Up to now, the design of this kind of materials shows some synthetic contradictions. However, the recently introduction of paramagnetic ligands in our group has allowed the obtaining several materials that show both characteristics.A first nanoporous molecular ferromagnet (referred as MOROF-1, Metal-Organic Radical Open-Framework) has been synthesized by the use of a paramagnetic metal ion such as Cu(II) and a perclorotrifenilmethyl radical trifucntionalized with three carboxylic functions (D. MASPOCH, NATURE MATERIALS, 2002, 2, 190). This material shows a really interesting nanoporous characteristics. The dimensions of their channels are around 3 nm. Furthermore, the desorption and absorption of solvent molecules (ethanol or methanol) produces surprising structural changes: this material shows a similar behavior of that a molecular sponge; giving an excellent characteristics to behave as a sensor for solvents such as ethanol or methanol. Furthermore, this highly porous structure shows a magnetic ordering at low temperatures.This material has been accompanied by two new materials, both with interesting porosity and magnetic properties. MOROF-2 (D. MASPOCH ET AL., CHEM COMMUN., 2004, 1164) is a paramagnetic solid with a new topology and helicoidal channels. Moreover, MOROF-3 also shows a magnetic ordering and a highly porosity characteristic. On the other hand, the use of this radicals as paramagnetic organic building-blocks linked by hydrogen-bonds has allowed the design of the first purely organic nanoporous and magnetic materials, which are stable in absence of solvent molecules and are stable at high temperatures (275 ºC). Thus, the proper packing of PTMDC radical forms a paramagnetic molecular material (POROF-1) with a structure composed by hydrophobic nanocontainers of 1 nm connected by narrow hydrophilic windows of 5 Å (D. MASPOCH ET AL., J. AM. CHEM. SOC., 2004, 126, 730). Furthermore, PTMTC radical forms a second purely organic material (POROF-2), which are magnetically ordered (D. MASPOCH, ANGEW. CHEM. INT. ED., 2004, 43, 1828).It has been also showed the possible use of this new nanoporous and magnetic molecular materials for the formation of new multifunctional molecular materials. With this aim, a new porous materials that combines channels covered by chiral groups and interesting magnetic properties has been obtained.

L'objectiu principal del present estudi és aprofundir, des d'un punt de vista teòric i experimental en els aspectes cinètics i mecanístics de les fragmentacions unimoleculars de radicals anions que evolucionen per donar lloc a radicals i anions. Tractarem de veure el comportament que presenten aquests radicals anions en diferents famílies d'espècies i extreuren conclusions que ens permetin veure quin patró segueixen. El treball s'agrupa en diferents capítols (del capítol 4 al capítol 6), segons el tipus d'enllaç estudiat, i el qual és susceptible de ser fragmentat una vegada generat l'anió radical. / The main purpose of this study is to deeply investigate, in a theoretical and experimental point of view, the kinetics and mechanisms of unimolecular radical anion fragmentations to obtain corresponding radical and anions. We will discuss about the behavior of these radical anions in different families of molecules to achieve concrete reasons to explain these fragmentations. The study is presented in different chapters (from 4 to 6), depending on the type of bond studied which is susceptible to be broken.

Thesis (Ph. D.)--University of Chicago, Department of Chemistry, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--York University, 1999. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 151-163). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ39292.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

No description available.

No description available.

A summary of tin hydride mediated reactions in generating radicals in organic synthesis is presented, together with some of the many alternative methods now available for conducting radical reactions. Particular attention has been given to the iminyl radical and the development of tin-free organic radical precursors. This introduction is followed by three chapters describing research on the development of two new sources of iminyl radicals and their application in syntheses of aza- heterocyles. O-Phenyl oxime ethers are the first iminyl radical precursors described in the thesis. Microwave thermolyses of oxime ethers released iminyl and phenoxyl radicals under comparatively mild conditions and with short reaction times. Few microwave-assisted synthetic methods, based around radical intermediates, are known. The mild and neutral conditions associated with radical chemistry, and the ability of radicals to perform intramolecular cyclisations, together with the virtues of MAOS, make their combination a very useful tool in syntheses of aza-heterocycles. A comprehensive study of intramolecular additions of iminyl radicals onto several radical acceptors, alkenes, alkynes, phenyl rings and indoles, is described. Furthermore, a wide range of nitrogen heterocyles with potential biological activity was prepared making use of this methodology. Intramolecular iminyl radical cyclisation onto imines via microwave irradiation was another process extensively studied. Microwave assisted syntheses of dihydroquinazolines and quinazolines are described. The precursor O-phenyl oxime ethers enable imine formation to be assimilated with iminyl radical generation before subsequent cyclisation. Clean, fast and high yielding methodology was therefore developed for the syntheses of these highly interesting heterocycles which form the basis of many pharmaceutical products. Dioxime oxalates were the second type of precursor investigated as sources of iminyl radicals. Homolytic cleavage of their N-O oxime bonds occurred on photolysis releasing two molecules of CO₂ and two iminyl radicals in a clean and atom-efficient process. A facile route to dioxime oxalates with a range of radical acceptors in suitable positions is described. ESR spectroscopy was used to demonstrate that dioxime oxalates dissociate on photolysis to give iminyl radicals in the presence of photosensitizer. This technique also confirmed the proposed mechanisms of radical cyclisation onto double bonds and several 2-azacyclopentylmethyl radicals were characterized by ESR spectroscopy. In several instances both the uncyclized iminyl radical, and the cyclised C-radical, could be simultaneously detected, and their concentrations determined. ESR spectroscopy was then profitably used to determine 5-exo-cyclization rate constants of iminyl radicals onto double bonds. Finally, the syntheses of several heterocycles from dioxime oxalates are described. Photolytic dissociation of dioxime oxalates containing alkenyl groups yielded iminyl radicals that ring closed to 3,4-dihydro-2H-pyrroles in toluene solution. The syntheses of phenanthridines, and the natural product trisphaeridine, were also accomplished by UV irradiation of dioxime oxalates containing aromatic rings as the radical acceptor.