Synthesis and Reactivity of Novel Boron- and Aluminium-containing Heterocycles

The first part of this thesis addresses a major challenge in borole synthesis: the isolation of monomeric boroles featuring an alkyl-substituted backbone. In this work, an aluminium-boron exchange is introduced as a novel synthesis strategy for alkylated boroles, with a sterically demanding aryl group at the boron atom to prevent dimerisation, allowing access to the first monomeric derivatives of this type. Computational and experimental data reveal that the alkyl substituents lead to remarkable modifications in the optical and electronic properties of the boroles compared to their perarylated counterparts. The high reactivity of the boroles, owed to their antiaromaticity, was exploited in various reactions. The second part of the thesis focusses on the synthesis of chiral 3a,6a-dihydroborolo[3,2 b]boroles. Boroloboroles have generated interest as building blocks in polyaromatic hydrocarbons (PAHs) with potential applications as semiconductors, but the known synthetic routes towards them are limited. In this work, chiral 3a,6a-dihydroborolo[3,2-b]boroles are obtained in one diastereoselective step from the reactions of ortho-(dihaloboryl)arenes with stannole derivatives via a complex rearrangement of 1-borolyl-2-(dihaloboryl)-arene intermediates. Given the potential for varying the fused arene/PAH moiety and the stannole substitution pattern this route is highly promising for accessing a wide range of fully conjugated boroloborole-containing PAHs. The last part of the thesis deals with the synthesis and investigation of novel backbone-functionalised 9 aluminafluorenes, which, other than their boron-counterparts, remain largely unexplored. In this work, novel 9 aluminafluorenes functionalised with electron donating methoxy groups are introduced. CV measurements and DFT calculations reveal clear divergences from analogous non-backbone functionalised aluminafluorenes.