Abstract
The reactivity of β-diketiminato alkylmagnesium, hydridomagnesium and hydridocalcium bases toward 1-methylimidazole, 1-tert-butylimidazole and 1-methylbenzimidazole enables the C-magnesiation and calciation of this family of N-heterocyclic molecules. Although 1-methylimidazole, 1-tert-butylimidazole, and 1-methylbenzimidazole are deprotonated at their C-2 positions by both the magnesium alkyl and hydride derivatives, these reagents can also leverage a level of regiodivergent kinetic discrimination and resultant C-4 metallation. In contrast to the straightforward C-2-deprotonation of 1-methylbenzimidazole provided by the magnesium hydride, a rapid cascade of apparent deprotonation, imidazole ring opening and twofold C[sbnd]C coupling was induced by the analogous calcium reagent. This process provides a tricalcium species comprising an unprecedented trianionic unit, which may be considered as a trimethylenemethane dianion isostere equipped with a pendent amide donor. While attempted boron functionalisation of the imidazolyl anions of the magnesium derivatives of 1-methylimidazole and 1-methylbenzimidazole with pinacolborane (HBpin) was unsuccessful, the 1-tert-butylimidazolyl analogue provided the C-2-borylated product irrespective of the position of initial C-2 or C-4 deprotonation. Although the calcium congeners resulting from 1-methylimidazole and 1-tert-butylimidazole were deduced to form similarly borylated products, study of their onward reactivity was prevented by their instability toward Schlenk-type redistribution in solution.
Original language | English |
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Article number | 117255 |
Journal | Polyhedron |
Volume | 264 |
Early online date | 12 Oct 2024 |
DOIs | |
Publication status | E-pub ahead of print - 12 Oct 2024 |
Data Availability Statement
Data will be made available on request.Funding
We acknowledge the Petroleum Technology Development Fund (PTDF) of Nigeria for the provision of a PhD scholarship for BO-E.
Funders | Funder number |
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Petroleum Technology Development Fund |
Keywords
- Calcium
- Hydrides
- Imidazoles
- Magnesium
- Organometallics
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry