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Published on: May 11, 2017
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Allosteric Differentiation of Al(I) Reactivity
Han-Ying Liu1, Jakub Kenar1, Henry T W Shere1
1Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|April 11, 2025
Summary
Dimeric potassium alumanyl reacts with alkynes to form aluminacyclopropenes. With controlled stoichiometry, it also undergoes phenyl C-H activation, suggesting cooperative steps and allosteric kinetic discrimination.
Area of Science:
- Organometallic Chemistry
- Main Group Chemistry
- Synthetic Chemistry
Background:
- Potassium alumanyl complexes are versatile reagents in organometallic synthesis.
- Alkyne cycloaddition reactions are fundamental in constructing cyclic organic frameworks.
- Understanding reaction selectivity and mechanisms is crucial for developing new synthetic methodologies.
Purpose of the Study:
- To investigate the reactivity of dimeric potassium alumanyl with various alkynes.
- To explore the influence of stoichiometry on reaction outcomes, including cycloaddition and C-H activation.
- To elucidate the mechanistic pathways governing these transformations.
Main Methods:
- Synthesis and characterization of dimeric potassium alumanyl.
- Reactions with substituted phenylalkynes under varying stoichiometric conditions.
- Spectroscopic analysis (NMR) and X-ray crystallography for product identification.
- Computational studies (theoretical calculations) to support mechanistic proposals.
Main Results:
- Exclusive formation of aluminacyclopropene derivatives when using two equivalents of alkyne.
- Co-occurrence of alkyne cycloaddition and para-C-H activation of phenyl substituents with equimolar stoichiometry.
- Identification of cooperative steps and allosterically influenced kinetic discrimination in the observed selectivity.
Conclusions:
- Stoichiometry plays a critical role in directing the reactivity of dimeric potassium alumanyl towards either cycloaddition or C-H activation.
- The observed selectivity is attributed to a combination of cooperative effects and kinetic control.
- This study provides insights into the complex reaction mechanisms involving main group organometallic reagents and unsaturated substrates.
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