Thesis advisor: James Morken / This dissertation will present two main projects focusing on the construction of enantiomerically enriched α-boryl organometallic reagents by transition metal catalysis. The first project describes the development of a platinum-catalyzed enantioselective hydrosilylation reaction of alkenyl boronic esters, which provides a general and efficient route to α-borylsilane species. Such species are configurationally stable and exhibit significant synthetic utilities. The second project depicts a nickel-catalyzed enantioselective carbozincation reaction of vinyl boronic esters, which for the first time giving approach to enantioenriched α-borylzinc reagents. These reagents possess good configurational stability at low temperatures and can participate in copper-catalyzed allylation, palladium-catalyzed Negishi cross-coupling and electrophilic halogenation reactions in stereospecific fashion to furnish a broad array of chiral boronic esters. These compounds are important and versatile building blocks in organic synthesis and utilized in the synthesis of (–)-aphanorphine and (–)-enterolactone. Detailed mechanistic studies were carried out, which revealed a nickel(I)-based redox neutral catalytic cycle. The properties of α-borylzinc compounds were also studied by 1H NMR and enabled the development of a stereoconvergent cross-coupling of racemic α-borylzinc reagents. Such catalytic system is also effective for an enantioselective silylzincation of vinyl boronic esters. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Cette thèse a été consacrée à la formation et l'utilisation de 4-amino- et 4-hydroxy-1-allénylmétaux. Deux méthodes de préparation stéréosélective et stéréospécifique des 4-sulfinamido- et 4-acétamido-1-allénylsilanes ont été développées. Ces deux voies reposent sur la réaction du tris(diméthylphényl)zincate de lithium avec les N-tert-butanesulfinylaziridines acétyléniques d'une part, et les acétates propargyliques de -acétamidoalkyle d'autre part. L'étendue et les limites de ces deux méthodes complémentaires ont été explorées. La fluorodésilylation électrophile des 4-acétamido-1-allénylsilanes avec le Selecfluor® a ensuite permis d'accéder de façon stéréosélective aux -fluoroacétates propargyliques correspondants. Un modèle d'état de transition a été proposé pour expliquer la différence de transfert de chiralité observée. Finalement, plusieurs voies d'accès aux 4-sulfinamido- et 4-sulfonylamido-1-allénylzincs par réarrangement métallate-1,2 de tris(diméthylphényl)zincates de lithium acétyléniques, obtenus à partir des N-tert-butanesulfinyl- et N-tert-butanesulfonylaziridines, se sont révélées infructueuses. En revanche, dans le cadre d'une collaboration franco-belge, l'étude de la borylation cupro-catalysée d'époxydes acétyléniques a donné des résultats prometteurs et a ouvert une nouvelle voie d'accès stéréosélective aux 4-hydroxy-1-allénylboranes. / During this research, the synthesis and use of 4-amino- and 4-hydroxy-1-allenylmetals have been studied.Two stereoselective and stereospecific syntheses of 4-sulfinamido- and 4-acetamido-1-allenylsilanes have been developed. These two synthetic routes rely on the reaction of lithium tris(dimethylphenylsilyl)zincate with acetylenic N-tert-butanesulfinylaziridines on one hand, and propargylic -acetamidoalkyl acetates on the other hand. The scope and limitations of these two complementary methods have been explored. The electrophilic fluorodesilylation reaction of 4-sulfinamido- and 4-acétamido-1-allenylsilanes with Selecfluor® gave access to propargylic -fluoroacetates in a stereoselective manner. A transition state model has also been postulated to explain the level of the chirality transfer observed. Finally, different synthetic routes towards 4-sulfinamido- and 4-sulfonylamido-1-allenylzincs through the 1,2-metalate rearrangement of acetylenic lithium tris(dimethylphenylsilyl)zincates, obtained from N-tert-butanesulfinyl- and N-tert-butanesulfonylaziridines, were proven to be unsuccessful. However, in the context of a French-Belgian collaboration, the study of the copper-catalyzed borylation of acetylenic epoxides led to promising results and paved the way for a new stereoselective synthesis of 4-hydroxy-1-allenylboranes.