La tesis se centra en el estudio del mecanismo de las reacciones de cicloisomerización de 1,6-eninos catalizada por complejos de oro(I). Evidencia experimental de la existencia de los intermedios propuestos se ha obtenido mediante la reacción de atrapamiento intermolecular de dichos intermedios, con alquenos, mediante la reacción de bisciclopropanación, y también por adición externa de nucleófilos. Por otra parte, la reacción de cicloadición [4 + 2] de aril eninos sustituidos fue estudiada. Esta reacción se ha utilizado como metodología clave para la síntesis de productos naturales como la familia de las picnanthuquinonas, También se ha estudiado el mecanismo de trasposición por rututa de enlace simple o doble y la formación de ciclobutenos en la reacción de 1,6-eninos aril substituidos. / This Thesis is focused on the mechanism of the cycloisomerization reaction of 1,6-enyes catalyzed by gold(I) complexes. We obtained experimental evidence for the existence of the proposed intermediates by intermolecular trapping with alkenes, through a biscyclopropanation reaction and by reaction with external nucleophiles. On the other hand, the [4 + 2] cycloaddition reaction of substituted aryl enynes was studied. This reaction was used in an approach for the total synthesis of natural products such as the pycnanthuquinones. We have also studied the mechanism of the simple/double cleavage rearrangement and the formation of cyclobutenes in the reaction of aryl substituted 1,6-enynes. Moreover, new silver and copper complexes were prepared and structurally characterized. The new complexes were assayed in the cycloisomerization and cyclopropanation reactions. Metal-arene interactions were also studied.

New Gold(I) Alkynophylic CatalystsAutor: Mihai RaducanDirector: Antonio M. EchavarrenResumen para TESEO en castellano: El uso de nitrilos aromáticos ricos en electrones permitió el aislamiento de nuevos catalizadores catiónicos de oro(I) estables al aire. [Au(tmbn)2](SbF6) (tmbn = 2,4,6-trimethoxybenzonitrilo), sintetizado a partir de AuCl, sirve como precursor para otros complejos de oro(I). Sólo uno o los dos ligandos tmbn pudieron ser sustituidos con ligandos fosforados, nitrogenados o carbonados y los complejos resultantes se pudieron aislar mediante cristalización. Se estudió la actividad catalítica de estos complejos en la ciclación de 1,6-eninos y reacciones relacionadas. También se han sido aislado y caracterizado catalizadores de oro conteniendo fosfatos quirales.En presencia de complejos de oro(I), los 1,6-eninos conteniendo alcoholes o éteres propargílicos sufren una migración estereoespecífica intramolecular 1,5 dando lugar a cationes de alil-oro. Estos intermedios se pueden atrapar intra- o intermolecularmente con alquenos, dienos o éteres bencílicos. Esta reacción estereoespecífica puede dar lugar a compuestos relacionados con los sesquiterpenos 4-epiglobulol, 4-aromadendreno, con los carotanes y los schinsanwilsonenos.New Gold(I) Alkynophylic CatalystsAutor: Mihai RaducanDirector: Antonio M. EchavarrenResumen para TESEO en inglés: Employing electron rich aromatic nitriles as labile ligands gold(I) catalysts were isolated as air stable solids. [Au(tmbn)2](SbF6) (tmbn = 2,4,6-trimethoxybenzonitrile), synthesized starting from AuCl, serves as a precursor for other gold(I) complexes. Only one or both of the tmbn ligands could be substituted by N, P, or C ligands and the resulting complexes could be isolated by crystallization. The catalytic activity of these complexes was studied for the cyclization of 1,6-enynes and other related reactions. Gold(I) catalysts containing chiral phosphates were also isolated and characterized. Upon activation with Au(I) cationic catalysts, 1,6-enynes with propargyl alcohols and ethers undergo stereospecific intramolecular 1,5-migration via allyl-gold cations. These intermediates were trapped inter- or intramolecularly with alkenes, dienes and benzyl ethers. This stereospecific reaction can lead to compounds, related to the sesquiterpenes 4-epiglobulol and 4-aromadendrene, the carotanes and the schinsanwilsonenes.

Organoboron derivatives represent an important class of compounds due to the versatility of the carbon-boron bond in a variety of chemical reactions. Boron-containing compounds have garnered increasing attention as synthetic intermediates and medicinal agents. Therefore, the introduction of carbon-boron bonds to organic molecules continues to be an important field of study. This dissertation describes novel methodology for the regio- and stereo-selective introduction of carbon-boron bonds to generate β-borylacrylonitrile and 1-boryl-1,3-enyne products. Propiolonitriles are intriguing research targets due to the electron-withdrawing nature of the cyano group on the adjacent alkyne. In this dissertation, we developed a phosphine-catalyzed regio- and stereo-selective hydroboration of propiolonitriles to generate novel β-borylacrylonitriles in up to 89% yield and 97:3 (E)-selectivity. These products were converted to the corresponding postassium 1,2-vinylcyanotrifluoroborate salts and demonstrated applications in oxidation and Suzuki-Miyaura cross-coupling reactions. Interestingly, 31P and 13C NMR studies suggest that this hydroboration reaction proceeds in a 1,2-phosphine addition pathway instead of a canonical 1,4-conjugate addition pathway. We also developed a transition metal-free cis hydroboration of 1,3-diyne substrates. In the presence of catalytic amounts of tri-n-butylphosphie and the unsymmetric diboron reagent pinBBdan, 1-boryl-1,3-enyne products were generated in up to 63% and >99:1 (Z)-selectivity. These 1,8-diaminonaphthalene products can be converted to the corresponding pinacolboranes or trifluoroborate salts. They also demonstrated applications in protodeboronation and Suzuki-Miyaura cross-coupling reactions. We propose that this hydroboration occurs via a nucleophilic boron addition mechanism. / Doctor of Philosophy / Incorporating boron into organic molecules provides access to a variety of otherwise difficult chemical reactions. Therefore, our laboratory seeks to develop new methods for synthesizing organoboron compounds. A major goal of our work is to develop transition metal-free reactions due to the expense and environmental impact of transition-metal mediated methodology. This dissertation reports two new methods for installing boron to organic molecules without the use of transition metals. The reported reactions utilize mild conditions to selectively generate functionalized products, and applications of these products are demonstrated. Chapter 1 describes a hydroboration reaction of propiolonitrile derivatives to afford (E)-β-borylacrylonitrile products. Notably, this reaction proceeds via a unique mechanism, contrasting that of similar reported reactions. Chapter 2 reports a transition metal-free hydroboration of 1,3-diynes to afford (Z)-1-boryl-1,3-enyne products. These products are structurally similar to relevant molecules in medicinal, polymer, and synthetic chemistry.

Dans ce manuscrit, nous avons décrit l'accès aux dérivés bicyclo[2.1.0]pentanes via deux réactions métalo-Catalysées, à savoir une cycloisomérisation d’énynes-1,6 catalysée par le platine et la cyclopropanation de cyclobutènes catalysée par le ruthénium à l’aide carboxylates propargyliques tertiaires. Tout d'abord, nous avons développé la formation, catalysée par Pt(II), de cyclobutènes à partir d’énynes-1,6 reliés par un hétéroatome (azote ou oxygène) pour former les aza- et oxa-Bicyclo[3.2.0]hept-6-Ènes respectivement. Il est montré que la présence de substituant(s) alkyle(s) en position propargylique et l'utilisation de solvants faiblement coordonnés, tels que le DMA sont les caractéristiques principales favorisant la formation de cyclobutènes. Ensuite, la disponibilité de cyclobutènes issus de la cycloisomérisation des 1,6-Énynes a permis leur utilisation pour la construction de systèmes bicyclo[2.1.0]pentanes par la mise en œuvre d’une cyclopropanation catalysée par le ruthénium utilisant les carboxylates propargyliques tertiaires. Ces composés sont obtenus sous la forme d’un diastéréomère unique avec des rendements bons à excellents. Cette réaction fournit une alternative sûre aux méthodes utilisant les dangereux composés diazo précurseurs de carbène pour générer les bicyclo[2.1.0]pentanes fonctionnalisés dans des conditions douces et avec des rendements élevés. / In this manuscript, we have described an access to bicyclo[2.1.0]pentanes via two metal-Catalyzed reactions, namely a platinum-Catalyzed cycloisomerization of heteroatom-Tethered 1,6-Enynes and the subsequent ruthenium-Catalyzed cyclopropanation of cyclobutenes with tertiary propargyl carboxylates.First, we have developed the Pt(II)-Catalyzed formation of cyclobutenes from nitrogen and oxygen-Tethered 1,6-Enynes to form aza- and oxabicyclo[3.2.0]hept-6-Enes respectively. It is shown that the presence of alkyl substituent(s) at propargyl position and the use of weakly coordinating solvents such as DMA are the key elements favoring the formation of cyclobutenes.Second, the availability of cyclobutenes from the cycloisomerization of 1,6-Enynes has allowed their utilization for the construction of strained bicyclo[2.1.0]pentane structures as single diastereomers in good to excellent yield through a ruthenium-Catalyzed cyclopropanation. It provides a safe method which avoid the use of the hazardous diazo compounds precursors of carbenes to generate functionalized bicyclo[2.1.0]pentane frameworks in high yields under mild conditions.

Cette thèse porte sur les réactions de cyclisation des 1,6-enynes impliquant des catalyseurs de ruthénium. Trois types différents de cyclisation ont été élaborés à partir de précurseurs facilement disponibles, tels que les 1,6-enynes et alcynes. Dans un premier temps, une nouvelle cyclisation hydroalcynylante des 1,6-enynes, à l'aide d'alcynes terminaux comme co-réactifs, catalysée par le ruthenium a été explorée. Cette réaction fournit une méthode de synthèse de cycles à cinq chaînons doté d'un motif 1,5-enyne exocyclique. Un complexe du ruthenium neutre et riche en électrons, Cp*Ru(cod)Cl, s'est avéré être le catalyseur de choix de ces transformations. Dans un deuxième temps, en utilisant le même complexe, la cycloaddition [2+2+2] des 1,6-enynes et alcynes catalysée par le ruthénium a été développée. Les alcynes internes et terminaux sont appropriés pour accéder en une seule étape aux bicyclohexadienes avec de hauts rendements. Une bicycloannulation inhabitelle des 1,6-enynes, intégrant un atome d’azote, catalysée par le ruthénium a également été élaborée. Pour ces cyclisations, seul un complexe du ruthénium électrophile et alkynophile tel que [RuCl2(CO)3]2 a été en mesure d'effectuer la réaction. La formation exclusive des 3-azabicylo[4.1.0]hept-1-enes a été observée avec les 1,6-enynes dotés d'une unité alcyne interne. Ces réactions de cyclisation, respectant le principe des réactions à économie d’atome, sont discutées et sur la base de leur mécanisme de formation. / This dissertation focuses on cyclization reactions of 1,6-enynes involving ruthenium catalysts. Three different types of cyclization were developed from readily available precursors, such as 1,6-enynes and alkynes. In one application, a novel ruthenium-catalyzed hydroalkynylative cyclization of 1,6-enynes using terminal alkynes as co-reactants was explored. This reaction provides and entry to five-membered rings featuring an exocyclic 1,5-enyne motif. A neutral electron-rich ruthenium complex Cp*Ru(cod)Cl proved to be the catalyst of choice for these transformations. In another application, using the same complex, the ruthenium-catalyzed [2+2+2] cycloaddition of 1,6-enynes and alkynes was developed. Both internal and terminal alkynes were suitable substrates to access bicyclohexadienes with high yields in a single step. An intriguing ruthenium-catalyzed bicycloannulation of nitrogen-tethered 1,6-enynes has also been developed. For these cyclizations, only the electrophilic and alkynophilic ruthenium complex [RuCl2(CO)3]2 was able to perform the reaction. The exclusive formation of 3-azabicylo[4.1.0]hept-1-enes was observed with 1,6-enynes featuring an internal alkyne unit. These cyclization reactions fulfil the atom-economical reactions principle and are discussed on the basis of their mechanisms of formation.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work describes the synthesis of a series of twenty 4-[alkyl (aryl) (2-propinyl amino)-3-alken-2-ones], [R2C(O)CH=C(R1)N(R)(CH2C≡CH), where R2 = CF3, CCl3, CO2Et; R1 = Me, Et, Pr e R= Pr, Ph, Bn, 4-MeC6H4] obtained with 70-95% yield throught a reaction of 1,4-addition followed by substitution between propargylamines [NH(R)(CH2C≡CH), where R= Pr, Ph, Bn, 4-MeC6H4] and 4- alkoxy-3-alken-2-ones [R2C(O)CH=C(R1)(OMe), where R2 = CF3, CCl3, CO2Et, and R1= Me, Et, Pr], using acetonitrile as solvent, room temperature or under reflux, depending on substrates used. From the series of twenty 4-[alkyl(aryl) (2-propinylamino)]-3-alken-2-ones], nine were employed in cycloisomerization reactions using AgNO3 as catalyst and CHCl3 as solvent, at room temperature, which provided a series of eight 1,2-dihydropyridine 1-(R), 5-(C(O)R2) and 6-(R1) substituted with 70-90% yield, where R = Pr, Bn, Ph, 4-MeC6H4; R1 = Me, Et, Pr; R2 = CF3, CO2Et. In only one case the cycloisomerization reaction produced a five-membered heterocycle which was characterized as 4-methyl-1-propyl-3-trifluoroacetyl pyrrole. In this work was also studied the use of dimethylamino vinyl ketones [R4C(O)CH=CHNMe2, where R4= 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-NO2C6H4] and terminal alkynes [R3C≡C-H, where R3= Pent, Ph], using BuLi as base, BF3.OEt2 as catalyst and THF as solvent furnishing a series of eninones with 65-80% yield. / Neste trabalho é descrita a síntese de uma série de vinte 4-[alquil(aril) (2-propinilamino)]-3-alquen-2-onas [R2C(O)CH=C(R1)N(R)(CH2C≡CH), onde R2= CF3,CCl3, CO2Et; R1= Me, Et, Pr e R= Pr, Ph, Bn, 4-MeC6H4] obtidas com rendimentos entre 70-95%, através de uma reação de adição-1,4 seguida de substituição, entre aminas propargílicas [NH(R)(CH2C≡CH), onde R= Pr, Ph, Bn, 4-MeC6H4] e 4-alcóxi-3-alquen-2-onas [R2C(O)CH=C(R1)(OMe), onde R2= CF3, CCl3, CO2Et, e R1= Me, Et, Pr] empregando acetonitrila como solvente e utilizando temperatura ambiente ou refluxo, dependendo dos substratos utilizados. A partir de vinte 4-[alquil(aril) (2- propinilamino)]-3-alquen-2-onas, nove foram empregadas em reações de cicloisomerização utilizando AgNO3 como catalisador e CHCl3 como solvente, empregando temperatura ambiente, o que forneceu uma série de oito 1,2-diidropiridinas 1-(R), 5-(C(O)R2) e 6-(R1) substituídas, com rendimentos entre 70-90% onde R= Pr, Bn, Ph, 4-MeC6H4; R1= Me, Et, Pr; R2 = CF3, CO2Et. Em somente um caso, a reação de cicloisomerização produziu um heterociclo de 5 membros, sendo caracterizado como 4-metil-1-propil-3-trifluoracetilpirrol. Neste trabalho também foi estudado o uso de β-dimetilamino vinil cetonas [R4C(O)CH=CHNMe2, onde R4= 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-NO2C6H4] e alquinos terminais [R3C≡CH, onde R3 = Pent, Ph] em reações de acoplamento de organolítio via adição do tipo 1,4, utilizando BuLi como base, BF3.OEt2 como catalisador e THF como solvente para fornecer uma série de eninonas com rendimentos entre 65-80%.

Les cycloisomérisations d’énynes sont des réarrangements de substrats polyinsaturés qui permettent d’accéder à des composées cycliques ou polycycliques en une seule étape. Ces réactions sont catalysées par de nombreux métaux de transition et présentent un grand intérêt synthétique. Cependant, peu de cycloisomérisations énantiosélectives sont décrites dans la littérature. Des platinacycles carbéniques comportant une monophosphine comme ligand chiral ont été développés au laboratoire. Ces complexes ont été utilisés avec succès dans la réaction de cycloisomérisation d’allylamides propargyliques en aza[4.1.0]heptènes ; des excès énantiomériques jusqu’à 97% ont été obtenus. Ce système catalytique a été étendu à la désymétrisation par cycloisomérisation d’allylamides propargyliques comportant deux unités vinyliques (ee jusqu’à 95%). Par la suite, ces catalyseurs ont été appliqués à la cycloisomérisation d’énynes-1,5 comportant un groupement oxygéné en position propargylique. Des excès énantiomériques allant jusqu’à 75% ont été mesurés. / Enyne cycloisomerisations induce the formation of cyclic or polycyclic compounds from unsaturated substrates in a single step. These réactions catalysed by transition metals have a great interest in organic synthesis. However enantioselective versions of thèse reactions remain rare. Carbenic platinacycles with chiral monophosphines as ligands have been developped in our team. These complexes have been successfully used in the cycloisomerisation of allylpropargylamides into azabicyclo[4.1.0]heptenes ; enantiomeric excess up to 97% have been attained. This catalytic system has been extended to the desymetrisation of allylpropargylamides bearing a second vinyl moiety (ee’s up to 95%). These catalysts have been used also in the cycloisomerisation of 1,5-enynes bearing an oxygene fonstion at the propargylic position. Enantiomeric excess up to 75% have been obtained.

There are immense efforts to install the trifluoromethyl group (CF3) into organic molecules since it significantly affects reactivity, as well as the biological and pharmaceutical properties of the molecule. The α-trifluoromethylacrylates are useful synthetic intermediates for the synthesis of trifluoromethyl-bearing nucleosides or peptides. However, methods to prepare such derivatives are scarce and suffer narrow substrate scope, lack of diastereoselectivity, use of costly reagents, and lack of user‐friendliness. Chapter 2 discusses the synthesis of α‐trifluoromethylacrylates from converting shelf-stable α‐trifluoroborylacrylates via a stereoretentive radical trifluoromethylation with inexpensive reagents NaSO2CF3 and TBHP with copper catalysis at room temperature. Under these conditions, a wide substrate scope afforded the (E)‐diastereomer exclusively in moderate to good yield. The reaction products' utility is demonstrated in synthesizing phenyl‐4H‐pyran, a potent and selective class of IKCa channel blockers. Branching out from metal-catalyzed reactions, Chapter 3 and 4 discusses metal-free organo-catalytic reactions which are more economical and greener. Boron-containing compounds are important in organic chemistry due to the different transformations that can be performed to afford useful synthetic intermediates and pharmaceuticals. Chapter 3 elaborates on the Borylation of 1,3-butadiynes, which are molecules that are widely used to synthesize biologically active molecules, polymers, and supramolecular tools under phosphine-catalyzed conditions. The reaction proceeds with both regio- and stereo-selectivity, and the boryl group is installed on the beta carbon to the alkyne in a trans fashion as established from 2D NMR and X-ray crystallography. The reaction products are converted into useful intermediates under Suzuki Miyuara, protodeborylation, etc. 31P NMR tudies were conducted to understand the mechanism of the reaction, which is supported by the DFT calculations revealing that phosphine attack is the most crucial step. A similar strategy was utilized with pinacol borane and tri-n-butyl phosphine catalyst to achieve borylation on ynamides (Chapter 4). A wide variety of ynamides underwent hydroboration to install the boron group in a regio- and stereoselective fashion. Under radical trifluoromethylating conditions, the boryl moeity was converted into the trifluoromethyl group to afford β-CF3 enamides. 31P NMR studies were conducted to elucidate the mechanism. Finally, chapter 5 provides insight into the synthesis of 1,2,4-Oxadiazoles which are privileged scaffolds in medicinal chemistry. The developed reaction occurs under metal-free conditions using sodium carbonate to couple N-hydroxylbenzenecarbonimodyl chlorides with nitriles. / Doctor of Philosophy / Installing fluorine in organic molecules significantly improves their pharmaceutical properties and the trifluoromethyl (CF3) group is one such group. Chapter 2 describes a simple, cost-effective method to synthesize trifluoromethylated compounds with readily available reagents under copper-catalyzed conditions, whereas in Chapters 3 and 4, a metal-free method is discussed. In comparison with metal catalysts, organo catalysts are less toxic, readily available, avoid contamination, and are more economic. Boron is used for different transformations in organic chemistry and for making medicinally relevant molecules. An organo-catalytic method to install boron on various substrates and potential applications of such molecules as synthetic intermediates are discussed. 1,2,4-Oxadizoles are molecules that are considered privileged scaffolds imparting pharmaceutical properties. Finally, in Chapter 5, a procedure to synthesize 1,2,4-Oxadiazoles under mild reaction conditions and readily available reagents are discussed.

Les réactions de cycloisomérisation d’énynes catalysées par les métaux de transition sont de puissants outils en synthèse organique: elles donnent accès, en une seule étape économe en atomes, à une variété de structures intéressantes mono- ou bicycliques, comportant des motifs 1,4-diène, 1,3-diène, cyclobutène ou cyclopropane. Afin d’accéder à de nouvelles molécules dérivées de monoterpènes, des 1,6- et 1,7-énynes à pont oxygène ont été préparés à partir de l’alcool péryllique, du nérol et de l’isopulégol, et leur réactivité dans les réactions de cycloisomérisation catalysées par des sels ou des complexes des métaux de transition a été étudiée. De nouvelles molécules bi- et tricycliques contenant des motifs cyclopropane, 1,3- ou 1,4-diènes ont ainsi été synthétisées. Toutes ces molécules ont été purifiées et caractérisées par RMN techniques. Différents systèmes catalytiques décrits dans la littérature ont été comparés : PtCl2, AuCl3, [AuCl(PPh3)/AgPF6] et Rh2Cl2(CO)4. Nous avons ainsi pu montrer que la nature du produit de la réaction dépendait surtout de la structure de l’ényne initial mais aussi du catalyseur mis en jeu. De plus nous avons mis en évidence que la cinétique et la sélectivité pouvaient être modifiées lorsque les réactions étaient faites sous une atmosphère de CO. Dans un second temps, une version asymétrique de la réaction a été explorée dans le cas de l’1,6- ényne dérivé de l’alcool péryllique, en préparant des complexes du platine ou de l’or portant des ligands phosphorés chiraux. L’excès diastéréoisomérique observé sur les deux cyclopropanes obtenus a ainsi pu être augmenté dans le cas des complexes de l’or (I), mais les valeurs restent encore modestes. Enfin, nous avons entrepris une étude préliminaire de la réaction de cycloisomérisation en milieu liquide ionique dans le but de concevoir un système efficace de recyclage du catalyseur. Différents liquides ioniques et différents solvants d’extraction ont été testés pour la réaction avec l’1,6-ényne dérivé de l’alcool péryllique. L’activité et la sélectivité des différents catalyseurs se sont avérées modifiées par rapport à la réaction dans le solvant toluène et des problèmes de reproductibilité sont apparus. Cette étude devra être poursuivie afin d’optimiser les conditions de réaction et de recyclage. / The transition metals catalyzed cycloisomerization reactions of enynes are a powerful tool in organic synthesis: they give access, in only one atom-economic step, to a variety of interesting mono- or bicyclic structures, comprising 1,4-diene, 1,3-diene, cyclobutene or cyclopropane moieties. In order to reach new molecules derived from monoterpenes, O-tethered 1,6- and 1,7- enynes were prepared starting from perillyl alcohol, nerol and isopulegol, and their reactivity in cycloisomerization reactions catalyzed by transition metals salts or complexes was studied. New bi- and tricyclic molecules containing cyclopropane, 1,3- or 1,4-dienes moieties were thus synthesized. All these molecules were purified and characterized by NMR techniques. Various catalytic systems described in the literature were compared: PtCl2, AuCl3, [AuCl(PPh3)/AgPF6] and Rh2Cl2(CO)4. We thus could show that the nature of the final product depended especially on the starting enyne structure but also on concerned catalyst. Moreover we highlighted that kinetics and selectivity could be modified under CO atmosphere. Analogously, an asymmetrical version of the reaction was explored in the case of the 1,6-enyne derived from perillyl alcohol by preparing platinum or gold complexes with chiral phosphorated ligands. The observed diastereoisomeric excess on two obtained cyclopropanes thus could be increased in the case of gold (I) complexes, but the values remain still modest. Finally, we undertook a preliminary study of the cycloisomerization reaction in ionic liquid with an aim of conceiving an effective system for catalyst recycling. Various ionic liquids and different extraction solvents were tested for 1,6-enyne derived from perillyl alcohol. The activity and the selectivity of various catalysts proved, resulted modified compared to the reaction in toluene and reproducibility problems appeared. This study will have to be continued in order to optimize the conditions of reaction and the catalysts recycling.

Thesis advisor: James P. Morken / This dissertation details the development, application and study of new palladium-catalyzed carbon-carbon bond forming strategies that generate synthetically useful enantioenriched small molecules. Controlled by a bidentate phosphine ligand, these transformations are thought to operate through a unique 3,3'-reductive elimination that leads to high regio- and stereoselectivity. Specifically, Chapter 1 introduces background on prior work that led to the first allyl-allyl coupling to deliver branched 1,5-dienes, and presents new computational studies on the origins of regioselectivity with mono- and bidentate ligands. Building on these studies, Chapter 2 describes the development of a diastereoselective allyl-allyl coupling of substituted allylboron reagents with allylic chloride electrophiles. To extend the scope of allyl-allyl coupling, Chapter 3 details further reaction optimization and mechanistic studies that have allowed for increasingly congested bond formations. In Chapter 4, a related allyl-propargyl coupling to give enantioenriched 1,5-enynes through stereospecific reactions and kinetic resolution is presented. These developments are accompanied by laboratory and computational data that provide a deeper understanding of reaction mechanisms and the origins of regio- and stereoselectivity. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.