Este trabalho compreende a síntese e caracterização de um novo catalisador magneticamente recuperável de CoO para oxidação alílica de alcenos. O catalisador foi preparado através da deposição de nanopartículas (de tamanho entre 2-3 nm) do metal cataliticamente ativo em nanopartículas de magnetita revestidas por sílica. A natureza magnética do suporte permitiu a fácil separação do catalisador do meio reacional após o termino das reações pela simples aproximação de um ímã na parede do reator. O catalisador pôde ser completamente separado da fase líquida, fazendo com que a utilização de outros métodos de separação como filtração e centrifugação, comumente utilizados em sistemas heterogêneos líquidos, fossem completamente dispensados. O catalisador foi inicialmente testado em reações de oxidação do substrato modelo cicloexeno e mostrou seletividade para a produção do produto alílico, cicloex-2-en-1-ona, que é reagente de partida de grande interesse para a síntese de diversos materiais na indústria química. As reações de oxidação foram realizadas utilizando-se apenas O2 como oxidante primário, dispensando o uso de oxidantes tóxicos como cromatos ou permanganatos, que não são recomendados do ponto de vista ambiental. O catalisador sintetizado mostrou ser reutilizável em sucessivos ciclos de oxidação, destacando-se o aumento da seletividade para a formação da cetona alílica conforme o catalisador perde atividade. A lixiviação da espécie ativa para o meio reacional, problema comum na catálise heterogênea, não foi observada. Um estudo cinético mostrou que mesmo no inicio da reação o catalisador tem seletividade para a ocorrência de oxidação alílica em detrimento da reação de oxidação direta que dá origem ao produto epóxido. Em todos os tempos estudados o produto principal da reação foi sempre a cicloexenona. Os estudos também revelaram que CoO é a espécie mais ativa quando comparado com Co2+, Co3O4 e Fe3O4 nas mesmas condições reacionais. O catalisador de CoO foi empregado na oxidação de monoterpenos mostrando alta seletividade para a formação dos produtos alílicos, resultando em derivados oxigenados altamente valiosos para a indústria de fragrâncias. / This master thesis describes the synthesis and characterization of a magnetically recoverable CoO catalyst for allylic oxidation of alkenes. The catalyst was prepared through the deposition of the catalytic active metal nanoparticles of 2-3 nm on silica-coated magnetite nanoparticles. The magnetic nature of the support allowed the easy separation of catalyst from the reaction medium after the completion of the reaction by simply placing a magnet on the reactor wall.The magnetic separation technique used was able to completely isolate the solid from the liquid phase, making the use of other separation methods such as filtration and centrifugation, commonly used in liquid heterogeneous systems, unnecessary.The catalyst was initially tested in the oxidation of cyclohexene, as a model substrate, and showed high selectivity to the formation of the allylic product, cyclohex-2-en-1-one, an interesting starting reactant for many reactions in the chemical industry. The oxidation reactions were performed using O2 as primary oxidant, eliminating the use of toxic oxidants such as chromate or permanganate, which are not environmentally friendly. The synthesized catalyst was found to be reusable in successive runs, with the increasing selectivity to the allylic ketone as the catalyst lost its activity. The leaching of active species to the reaction medium, a common problem in heterogeneous catalysis, was not observed. A kinetic study showed that even at initial times the catalyst is selective for the allylic oxidation despite the direct oxidation, which leads to the formation of the epoxy product. For all reactions studied in different times, the product was always cyclohexenone. The studies also revealed that CoO is the most active species when compared to Co2+, Co3O4 and Fe3O4 in the catalytic conditions studied. The CoO catalyst was used in the oxidation of monoterpenes and showed high selectivity for the allylic products, giving oxygenate derivatives of highly value for flagrance industry.

Chiral quaternary centers possessing a bond to nitrogen are an important class of amine compounds, however, methods for their enantioselective preparation remain sparse. The focus of my graduate research described herein has been the development of a novel rhodium-catalyzed regio- and enantioselective allylic aryl amination of tertiary trichloroacetimidates for the synthesis of amine-bearing quaternary centers (also termed α,α-disubstituted amines). Prior to our work, allylic carbonates and acetates had been successfully utilized in transition-metal catalyzed substitution reactions with anilines for the asymmetric synthesis of tertiary centers. In contrast, these electrophiles have not proven useful in dynamic kinetic asymmetric transformations (DYKAT) that yield enantioenriched amine products, and no reports describing the asymmetric preparation of α,α-disubstituted allylic aryl amines via allylic substitution are noted. Many of the ideas for development of our rhodium-catalyzed amination method were based upon the findings of Overman where linear allylic trichloroacetimidates are utilized in [3,3]-sigmatropic rearrangements and substitution reactions by oxygen nucleophiles under palladium (II) catalysis. Our method diverges from this previous work by application of branched allylic trichloroacetimidates where the olefin component is mono-substituted, and the use of a transition-metal complex capable of facile oxidative addition to an intermediate organometallic complex. We hypothesized that bidentate chelation of these substrates at the imidate nitrogen and the relatively unimpeded olefin by a rhodium (I) complex would lead to rapid ionization to an activated complex and competent electrophile for substitution by neutral aniline nucleophiles. This premise was supported by many control studies and resulted in the development of a highly regioselective amination of branched allylic trichloroacetimidates for the operationally simple synthesis of α-substituted and α,α-disubstituted allylic aryl amines. Work followed utilizing chiral diene ligands that rendered the reaction enantioselective for preparation of enantioenriched tertiary and quaternary amine-containing centers. A highlight of these studies is the first example of DYKAT using a tertiary electrophile and an aryl amine nucleophile. The reaction is of broad substrate scope, is tolerant of varied functionality and substitution patterns on the nucleophilic partner, and solves regioselectivity issues often encountered with some substrate and aniline classes. I end by showing the synthetic utility of our rhodium-catalyzed reaction by applying this method to the synthesis of enantioenriched amino acids and construction of 7-membered nitrogen-containing heterocycles by a 2-step DYKAT amination and olefin hydroacylation sequence.

This dissertation summarizes research efforts focused on the use of boron and transition metal halides to form new carbon-carbon and carbon-halide bonds. The boron halide mediated alkyne-aldehyde coupling reaction to generate 1,3,5-triaryl-1,5-dihalo-1,4-dienes was reinvestigated in an attempt to explain the stereochemistry observed during changing of both the mode of addition and the reaction temperature. Either (Z,Z)-1,4-dienes or (Z,E)-1,4-dienes can be the predominant product depending on reaction conditions used. This mechanistic investigation also led to the discovery of several novel reactions. These include the stereoselective preparation of (Z)-3-chloroallylic ethers from the reaction of alkenylboron dichlorides with aryl aldehydes in the presence of an amine; the titanium(IV) halide coupling of alkoxides and alkynes; the haloallylation of aryl aldehydes with boron trihalide using different allylmetals; and the base induced elimination of the haloallylated products to form 1,3-dienes. The results of these studies strongly imply a cationic mechanism. The new reactions described herein can be characterized as atom-efficient, environmentally friendly, and capable of generating the desired products in good to excellent yields.

This thesis deals with the preparation and use of chiralbispyridylamides as ligands in metal-catalyzed asymmetricreactions. The compounds were prepared by amide formation usingdifferent coupling reagents. Bispyridylamides havingsubstituents in the 4- or 6- positions of the pyridine ringswere prepared by functional group interconversion of the 4- or6- halopyridine derivatives. These synthetic approaches provedto be useful for various types of chiral backbones. Pseudo C2-symmetric bispyridylamides were also synthesizedby means of stepwise amide formation. The compounds were used as ligands in themicrowave-accelerated Mocatalyzed asymmetric allylic alkylationreaction. Ligands having ð-donating substituents in the4-positions of the pyridine rings gave rise to products withhigher branched to linear ratio. The catalytic reaction, whichproved to be rather general for allylic carbonates with anaromatic substituent, was used as the key step in thepreparation of (R)-baclofen. The Mo-bispyridylamide catalystprecursor was studied by NMR spectroscopy. Bispyridylamide complexes of metal alkoxides were alsoevaluated in the asymmetric addition of cyanide to aldehydesand the metal complexes involved were studied by NMRspectroscopy and X-ray crystallography. Chiral diamines wereused as additives to study the ring opening of cyclohexeneoxide with azide, catalyzed by Zr(IV)-bispyridylamidecomplexes. Various bispyridylamides were attached to solid supports oforganic or inorganic nature. The solid-supported ligands wereused in Mo-catalyzed asymmetric allylic alkylation reactionsand in the asymmetric addition of cyanide to benzaldehyde. Keywords:asymmetric catalysis, chiral ligand, pyridine,amide, allylic alkylation, enantioselective, cyanation,ring-opening, chiral Lewis acid.

<p>This thesis deals with the preparation and use of chiralbispyridylamides as ligands in metal-catalyzed asymmetricreactions.</p><p>The compounds were prepared by amide formation usingdifferent coupling reagents. Bispyridylamides havingsubstituents in the 4- or 6- positions of the pyridine ringswere prepared by functional group interconversion of the 4- or6- halopyridine derivatives. These synthetic approaches provedto be useful for various types of chiral backbones. Pseudo C₂-symmetric bispyridylamides were also synthesizedby means of stepwise amide formation.</p><p>The compounds were used as ligands in themicrowave-accelerated Mocatalyzed asymmetric allylic alkylationreaction. Ligands having ð-donating substituents in the4-positions of the pyridine rings gave rise to products withhigher branched to linear ratio. The catalytic reaction, whichproved to be rather general for allylic carbonates with anaromatic substituent, was used as the key step in thepreparation of (R)-baclofen. The Mo-bispyridylamide catalystprecursor was studied by NMR spectroscopy.</p><p>Bispyridylamide complexes of metal alkoxides were alsoevaluated in the asymmetric addition of cyanide to aldehydesand the metal complexes involved were studied by NMRspectroscopy and X-ray crystallography. Chiral diamines wereused as additives to study the ring opening of cyclohexeneoxide with azide, catalyzed by Zr(IV)-bispyridylamidecomplexes.</p><p>Various bispyridylamides were attached to solid supports oforganic or inorganic nature. The solid-supported ligands wereused in Mo-catalyzed asymmetric allylic alkylation reactionsand in the asymmetric addition of cyanide to benzaldehyde.</p><p><b>Keywords:</b>asymmetric catalysis, chiral ligand, pyridine,amide, allylic alkylation, enantioselective, cyanation,ring-opening, chiral Lewis acid.</p>

This thesis is focused on two main areas of organic synthesis, palladium-catalyzed functionalization of alkenes and allylic alcohols, as well as development of new allylboration reactions. We have developed a palladium-catalyzed selective allylic trifluoroacetoxylation reaction based on C−H functionalization. Allylic trifluoroacetates were synthesized from functionalized olefins under oxidative conditions. The reactions proceed under mild conditions with a high level of diastereoselectivity. Mechanistic studies of the allylic C−H trifluoroacetoxylation indicate that the reaction proceeds via (η3-allyl)palladium(IV) intermediate. Palladium-catalyzed regio- and stereoselective synthesis of allylboronic acids from allylic alcohols has been demonstrated. Diboronic acid B2(OH)4 was used as the boron source in this process. The reactivity of the allylboronic acids were studied in three types of allylboration reactions: allylboration of ketones, imines and acyl hydrazones. All three processes are conducted under mild conditions without any additives. The reactions proceeded with remarkably high regio- and stereoselectivity. An asymmetric version of the allylboration of ketones was also developed. In this process chiral BINOL derivatives were used as catalysts. The reaction using γ-disubstituted allylboronic acids and various aromatic and aliphatic ketones afforded homoallylic alcohols bearing two adjacent quaternary stereocenters with excellent regio-, diastereo- and enantioselectivity (up to 97:3 er) in high yield. The stereoselectivity in the allylboration reactions could be rationalized on the basis of the Zimmerman-Traxler TS model.

La catàlisi asimètrica es part de la síntesi asimètrica i fa possible la transformació de substrats pro-quirals o racèmics en productes quirals emprant quantitats catalítiques de compostos que contenen informació quiral. El disseny de nous lligands es l'etapa clau per a obtenir alts nivells de reactivitat i selectivitat. Els carbohidrats son uns dels membres més importants dintre de la "chiral pool".Aquesta tesi esta enfocada en el desenvolupament i aplicació en catàlisi asimètrica de nous lligands amb esquelet carbohidrat.Aquestos lligands foren aplicats amb èxit a la hidroformilació asimètrica catalitzada per Rh d'alquens monosubstituïts, interns disubstituïts i 1,1´-disubstituïts.L'efecte de les modificacions estructurals dels lligands 1,3-difosfit sobre els resultats catalítics a l'alquilació al·lílica catalitzada per Pd de compostos fenil-al·lílics ha sigut també estudiat en aquesta tesis. Finalment, els lligands 1,3-difosfit han sigut aplicats a l'estabilització de nanopartícules metàl·liques, i la seva aplicació a la hidrogenació de o- i m-metilanisol. / Asymmetric catalysis is part of the asymmetric synthesis and makes possible the transformation of a pro-chiral or racemic substrate into a chiral product using catalytic amounts of the compounds which contain the chiral information. The design of new ligands is perhaps the most crucial step to achieve the highest levels of reactivity and selectivity. Carbohydrates are the most prominent members of the "chiral pool".This thesis focus on the development and application in asymmetric catalysis of new 1,3-diphosphite with carbohydrate backbone. These ligands were successful applied in the Rh-asymmetric hydroformylation of monosubstituted, disubstituted internal and 1,1´-disubstituted alkenes.The effect of the structural modification of these 1,3-diphosphite ligands on the catalytic results of the Pd-allylic alkylation of phenyl-allyl compounds was also studied in this thesis. Finally, the 1,3-diphosphites ligands were applied to stabilize metal nanoparticles. These nanocatalysts were tested in the hydrogenation of pro-chiral o- and m-methylanisole.

Esta tesis doctoral se centró en la síntesis y la caracterización de nanopartículas metálicas (Pd, Ni, Pt) estabilizadas por varios tipos de ligandos y el uso de estas nanopartículas en reacciones de formación de nuevos C-C o C-heteroatomo: a) Reacción de substitución alílica catalizadas por Pd; b) Reacción de acoplamiento asimétrico de Suzuki-Miyaura; c) Reacción de acoplamiento de Suzuki-Miyaura; d) reacción de adición 1,4 de ácidos borónicos a cetonas. En cada una de estas reacciones se llevó a cabo la síntesis y caracterización de nanoparticulas metálica y complejos moleculares usando muchos tipos de ligandos en los sistemas moleculares y los sistemas análogos cataliazados por nanopartículas. Excelentes actividades y enatioselectividades fueron obtenidas en la reacción de alquilación y aminación alílica. Además, estos sistemas fueron reciclados usando líquidos iónicos. También, nuevos y selectivas nanoparticulas fueron sintetizadas y caracterizadas. Estas nanopartículas fueron usadas exitosamente en varias reacciones de formación de nuevos enlaces C-C. / This doctoral thesis focuses on the synthesis and characterization of metal nanoparticles (Pd, Ni, Pt) stabilized by several types of ligands and the used of these nanoparticles in new C-C or C-heteroatom bond formation reactions: a) Pd-catalysed asymmetric allylic substitution reactions; b) Pd-catalysed asymmetric Suzuki-Miyaura coupling reactions; c) Ni-catalysed Suzuki-Miyaura coupling reactions; d) Pt-catalysed 1,4-addition of phenylboronic acid to 2-cyclohexen-1-one reaction. For each reaction, the synthesis and characterization of metal nanoparticles and molecular complexes using several types of ligands were performed and both types of catalytic systems were tested in the appropriate reactions. Remarkably, excellent enantioselectivities using Pd/phosphite ligand were obtained in allylic substitution reaction. An efficient recovery of the catalytic system was carried out using ionic liquids as reaction medium. New active and selective nanoparticles were synthesized and characterized. These nanoparticles were applied successfully in various C-C bond formation reactions.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

This thesis describes research conducted since September 2006 in Prof. Robert Batey’s laboratory. The thesis is divided into four chapters. Chapter one presents a general introduction of domino reactions, sigmatropic rearrangements, and the allylic azide rearrangement. Several factors affecting the allylic azide rearrangement along with some respective examples are presented. Chapter two describes an efficient synthesis of azido unsaturated ester compounds using a microwave-assisted domino allylic azide / Johnson-Claisen rearrangement. The domino rearrangement reaction proceeds to give the azido ester compounds in good yield and excellent diastereoselectivity. The synthesis of vinyl epoxides and hydroxy allylic azides starting materials are also presented. In addition, other variants of Claisen rearrangements are briefly discussed. Chapter three describes a microwave-assisted domino allylic azide / Overman rearrangement process. The scope of the domino rearrangements, including an example involving an enantioenriched compound, is presented. The product of the domino rearrangements can be used as precursors to 1,2-vicinal diamines. Several functional group transformations and potential application of the product of the domino rearrangement are also described. Chapter four provides the synthesis of cis-2,5-disubstituted pyrrolidines from domino reduction / cyclization of γ-azido-α,β-unsaturated ketones. The overall process involves hydrogenation of the alkene and the azido group, followed by intramolecular cyclization and loss of H2O to form an imine, which is further reduced to give cis-2,5-disubstituted pyrrolidines. The reaction proceeds cleanly to give the products in high yield and with a very high diastereoselectivity ratio. In addition, the formation of pyrrolidinones via domino reduction / cyclication of γ-azido esters are also reported