Arylation with Bismuthonium Salts

Maggi, Lorenzo (2021) Arylation with Bismuthonium Salts. PhD thesis, University of Nottingham.

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Organobismuth reagents have been employed as electrophilic arylating agents since the 1980s, but both their synthesis and use in arylation reactions suffer from poor atom economy. Improvements in the economy of Bi-mediated arylation would render this potentially powerful methodology both general and convenient. This Thesis discusses two approaches towards this goal: arylation catalysed by bismuthonium complexes and synthesis and reactivity of heteroleptic complexes. In particular, the feasibility of a catalytic approach for the arylation of phenols was extensively explored. The investigation separated the overall transformation in three key steps: oxidation, transmetalation and arylation. Direct access to tetraarylbismuthonium salts from readily available triarylbismuth species was provided by a new oxidation- transmetalation sequence. Attempts to merge the arylation step with the previous two proved challenging. Intrinsic incompatibilities of some components of the system were identified. Time separation of the oxidation-transmetalation steps from the arylation phase allowed the overall transformation to be performed in one-pot, however, at the expense of the catalytic approach.

The formation of heteroleptic bismuthonium salts by introduction of a unique group in the transmetalation step was explored for more than eighty different groups. A library of bismuthonium salts was obtained, which allowed mechanistic studies to be carried out, focusing in particular on the ability to transfer the unique group to the substrate during the arylation phase. This chemoselectivity was modelled and the influence of both steric and electronic effects was identified. Attempts to enable the fully selective transfer of the unique group were made by linking together three of the four aryl groups of the bismuthonium salt. A novel bismatriptycene complex was synthesised for this purpose and its capabilities in the arylation reaction were explored, showing promising results.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Ball, Liam
Keywords: bismuth, arylation, phenols, bismuthonium salts
Subjects: Q Science > QD Chemistry > QD241 Organic chemistry
Faculties/Schools: UK Campuses > Faculty of Science > School of Chemistry
Item ID: 64271
Depositing User: Maggi, Lorenzo
Date Deposited: 24 Oct 2023 14:05
Last Modified: 24 Oct 2023 14:05

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