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Deuteration of boranes: catalysed versus non-catalysed processes
David J Nelson1, Jonathan D Egbert, Steven P Nolan
1EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
Dalton Transactions (Cambridge, England : 2003)
|February 7, 2013
Summary
This study reveals a dual reactivity pattern for B-H bonds. An iridium catalyst efficiently deuterates boronate esters, while boranes react without a catalyst, highlighting substituent effects in boron chemistry.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Boron Chemistry
Background:
- Boron-hydrogen (B-H) bonds exhibit diverse reactivity crucial for synthetic chemistry.
- Understanding factors influencing B-H bond activation is key for developing new catalytic methods.
- Previous studies have explored various reagents and catalysts for B-H bond functionalization.
Purpose of the Study:
- To investigate the reactivity of B-H bonds with a novel bis(N-heterocyclic carbene)-ligated iridium(III) complex.
- To explore the deuteration of boronate esters and compare it with the reactivity of boranes and 9-BBN.
- To elucidate the mechanistic basis for the observed dichotomy in reactivity.
Main Methods:
- Synthesis and characterization of the bis(N-heterocyclic carbene)-ligated iridium(III) complex.
- Deuteration reactions of boronate esters, borane, and 9-BBN using the iridium catalyst under various conditions.
- Analysis of reaction products using spectroscopic techniques to confirm deuteration and assess reaction efficiency.
Main Results:
- The iridium(III) complex efficiently catalyzes the rapid deuteration of boronate esters at room temperature with low catalyst loadings.
- Borane and 9-BBN undergo deuteration in the absence of the iridium catalyst, showing no reaction with the complex.
- The observed dichotomy is attributed to the inductive electron-withdrawing properties of boronic ester substituents.
Conclusions:
- A clear difference in B-H bond reactivity exists between boronate esters and simple boranes/9-BBN.
- The iridium catalyst is highly effective for the deuteration of boronate esters, offering a mild and efficient synthetic route.
- Substituent effects play a critical role in directing the reactivity of B-H bonds in catalytic and non-catalytic processes.
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