Increasing attention has recently been directed toward 1,2,3-triazole-containing compounds. With their unique properties and excellent stability, 1,4-disubstituted triazoles are readily accessible via the copper catalyzed azide alkyne cycloaddition (CuAAC). As compounds containing fused triazoles become common in pharmaceutical targets and biologically active substances, new strategies to synthesize this class of molecules are highly desirable. An efficient and highly modular approach toward the synthesis of three different heterocyclic motifs containing fused 1,2,3-triazoles is reported. The synthesis involved a Pd-catalyzed annulation of 5-iodo-1,2,3-triazoles, which were prepared by a Cu(I)-catalyzed cycloaddition of iodoalkynes and azides. This work demonstrates the versatility of iodotriazoles in Heck reactions and in direct arylations.

Increasing attention has recently been directed toward 1,2,3-triazole-containing compounds. With their unique properties and excellent stability, 1,4-disubstituted triazoles are readily accessible via the copper catalyzed azide alkyne cycloaddition (CuAAC). As compounds containing fused triazoles become common in pharmaceutical targets and biologically active substances, new strategies to synthesize this class of molecules are highly desirable. An efficient and highly modular approach toward the synthesis of three different heterocyclic motifs containing fused 1,2,3-triazoles is reported. The synthesis involved a Pd-catalyzed annulation of 5-iodo-1,2,3-triazoles, which were prepared by a Cu(I)-catalyzed cycloaddition of iodoalkynes and azides. This work demonstrates the versatility of iodotriazoles in Heck reactions and in direct arylations.

Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metallation-deprotonation (CMD) pathway. Competition experiments were conducted using N-oxides of varying electronic characters, and results revealed an enhancement of rate when using a more electron-deficient species which is in support of a CMD transition state. The effect of base on reaction rate was also examined and it was found that a carboxylate base was required for the reaction to proceed. This led to the conclusion that Pd(OAc)2 plays a pivotal role in the reaction mechanism as more than merely a pre-catalyst, but as a source of acetate base required for the C-H bond cleavage step.

Trichloroethylene, a simple and very inexpensive material, has been identified as a tri- and tetrafunctionalizable building block. A combination of selective palladium-catalyzed cross-coupling reactions with standard lithiation and electrophilic quenching yields a wide variety of unsaturated linear or cyclic compounds in excellent yields in few synthetic steps. Dichlorovinyl ethers, obtained from a nucleophilic displacement reaction with trichloroethylene, are the basic starting materials. Two sets of conditions have been developed to achieve the reaction of either electron-rich or –deficient phenols with trichloroethylene to give the resultant dichlorovinyl ethers in high yields. Site selective palladium-catalyzed cross-coupling for the specific functionalization of a single C-Cl bond was developed, and could install alkyl, alkenyl, alkynyl and (hetero)aryl moieties. The resulting electrophiles could be reacted with a second organometallic nucleophile forming trisubstituted, electron-rich alkenes, dienes, trienes or enynes in only two or three steps. Alternatively, the product from the first cross-coupling reaction could be isolated, deprotonated and quenched with an electrophile, then cross-coupled with a second organometallic nucleophile to give tetrasubstituted, electron-rich alkenes and dienes. In the course of studying the site selective cross-coupling, it was found that prolonged exposure of the C1-functionalized materials to palladium promoted an intramolecular C-H activation, forming 2-substituted benzofurans. This reaction proved to be very general, and a wide variety of benzofurans were synthesized, containing both electron-withdrawing and electron-donating group groups in the donor arenes, as well as alkyl, alkenyl, alkynyl and aryl functionalities at the 2-position. This method was also extended to the synthesis of 2-substituted indoles from anilines, trichloroethylene and boronic acids.

Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metallation-deprotonation (CMD) pathway. Competition experiments were conducted using N-oxides of varying electronic characters, and results revealed an enhancement of rate when using a more electron-deficient species which is in support of a CMD transition state. The effect of base on reaction rate was also examined and it was found that a carboxylate base was required for the reaction to proceed. This led to the conclusion that Pd(OAc)2 plays a pivotal role in the reaction mechanism as more than merely a pre-catalyst, but as a source of acetate base required for the C-H bond cleavage step.

Trichloroethylene, a simple and very inexpensive material, has been identified as a tri- and tetrafunctionalizable building block. A combination of selective palladium-catalyzed cross-coupling reactions with standard lithiation and electrophilic quenching yields a wide variety of unsaturated linear or cyclic compounds in excellent yields in few synthetic steps. Dichlorovinyl ethers, obtained from a nucleophilic displacement reaction with trichloroethylene, are the basic starting materials. Two sets of conditions have been developed to achieve the reaction of either electron-rich or –deficient phenols with trichloroethylene to give the resultant dichlorovinyl ethers in high yields. Site selective palladium-catalyzed cross-coupling for the specific functionalization of a single C-Cl bond was developed, and could install alkyl, alkenyl, alkynyl and (hetero)aryl moieties. The resulting electrophiles could be reacted with a second organometallic nucleophile forming trisubstituted, electron-rich alkenes, dienes, trienes or enynes in only two or three steps. Alternatively, the product from the first cross-coupling reaction could be isolated, deprotonated and quenched with an electrophile, then cross-coupled with a second organometallic nucleophile to give tetrasubstituted, electron-rich alkenes and dienes. In the course of studying the site selective cross-coupling, it was found that prolonged exposure of the C1-functionalized materials to palladium promoted an intramolecular C-H activation, forming 2-substituted benzofurans. This reaction proved to be very general, and a wide variety of benzofurans were synthesized, containing both electron-withdrawing and electron-donating group groups in the donor arenes, as well as alkyl, alkenyl, alkynyl and aryl functionalities at the 2-position. This method was also extended to the synthesis of 2-substituted indoles from anilines, trichloroethylene and boronic acids.

Nos travaux de thèse portent sur la mise au point de nouvelles méthodes de synthèse permettant l’accès de façon rapide et efficace à différents dérivés pyrazolo[1,5-a]pyrimidiniques diversement fonctionnalisés.La première partie de ce travail concerne l’étude et l’application de la condensation de la pyran-2-one avec les 5(3)-amino-3(5)-arylpyrazoles que ce soit par chauffage classique ou sous irradiation micro-onde. Par la suite, un nouveau procédé d’(hétéro)arylation pallado-catalysé direct régiosélectif a été mis à profit pour élaborer des pyrazolo[1,5-a]pyrimidines fonctionnalisées tant en position 3 que sur le méthyle situé sur le sommet 7 de la 5,7-diméthylpyrazolo[1,5-a]pyrimidine.Le dernier volet de ce mémoire a été consacré à la préparation des entités pyrazolo[1,5-a]pyrimidiniques substituées en position 7 par des motifs benzyliques et ce, via une procédure « one-pot », sous irradiation micro-onde, constituée d’une réaction d’arylation directe pallado-catalysée suivie d’une saponification-décarboxylation. / Our thesis works concern the development of new methods of synthesis allowing a rapid and effective access to variously functionalized pyrazolo [1,5-a] pyrimidines derivatives.First, we were explored the study and the application of the condensation of the pyran-2 one with 5(3)-amino-3 (5)-arylpyrazoles whether it is by classic heating or under microwaves. Indeed, we have described the first example of the direct and regioselective palladium-catalyzed (hetero)arylation of 5,7-dimethylpyrazolo[1,5-a]pyrimidine, the reaction may be inducted to occur at either an sp2 or an sp3 carbon atom.The last part of this report was dedicated to the preparation of some 7-substituted pyrazolo[1,5-a]pyrimidines via a one-pot two steps palladium-catalyzed direct CH-arylation followed by a saponification-decarboxylation.

Orientador: Carlos Roque Duarte Correia / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-06T00:38:56Z (GMT). No. of bitstreams: 1 Pastre_JulioCezar_M.pdf: 2844371 bytes, checksum: 6abfb0e87d60113816e3b01d9a02d6b9 (MD5) Previous issue date: 2005 / Mestrado / Quimica Organica / Mestre em Química

Detailed mechanistic studies on the palladium-catalyzed direct arylation of pyridine N-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C-H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metallation-deprotonation (CMD) pathway. Competition experiments were conducted using N-oxides of varying electronic characters, and results revealed an enhancement of rate when using a more electron-deficient species which is in support of a CMD transition state. The effect of base on reaction rate was also examined and it was found that a carboxylate base was required for the reaction to proceed. This led to the conclusion that Pd(OAc)2 plays a pivotal role in the reaction mechanism as more than merely a pre-catalyst, but as a source of acetate base required for the C-H bond cleavage step.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22457号 / 工博第4718号 / 新制||工||1737(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 大江 浩一, 教授 中村 正治, 教授 中尾 佳亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM