Contributions to Precise Skeletal Editing via Alkenylboranes

Identifier:  TDX:4509

Handle: https://hdl.handle.net/20.500.11797/TDX4509

Authors:  Dominguez Molano, Paula

Abstract:
Organoboron chemistry has concentrated significant attention due to its critical role in organic synthesis. Organoboron compounds are efficient tools that can be converted into various functional groups. This thesis introduces new methodologies for synthesising alkenyl boronic esters, exploring novel activation modes and reactivity trends to create unprecedented organoboron compounds. In this context, Chapter III demonstrates the stereospecific exchange of boryl groups between alkenylboranes and several diboron reagents, forming mixed diboranes. Mechanistic studies suggest that this process involves catalytic activation of diboron by an alkoxide. On the other hand, gem-diborylalkenes constituted a novel subclass with promising potential. In Chapter IV, the stereoselective cyclopropanation of unsymmetrical 2-aryl-1,1-diborylalkenes has been investigated, producing gem-bis(pinacolboryl)cyclopropanes with high enantioselectivities. The borylation of π-systems is an exceptionally versatile method for introducing new functionalities. Copper complexes have proven to be effective catalysts for incorporating boron into π-unsaturated systems, enhancing the nucleophilicity of otherwise unreactive diboron compounds. This thesis contributes new methodologies that provide access to unprecedented organoboron compounds, emphasizing protocol efficiency and product versatility. In Chapter V, the development of a novel 1,3-B/Cu shift mechanism has been studied, facilitating stereoselective electrophilic trapping and synthesising homoallyl diborated products via palladium-catalysed regioselective intramolecular cross-coupling. Moreover, Chapter VI establishes the method for the 1,4-boryl copper shift, achieving stereospecific carbon-to-carbon boryl migration and enabling the synthesis of functionalised cyclopentenes and valuable bicyclic systems.