Magnesium-catalysed hydroboration of pyridines: kinetic analysis and poly-pyridine dearomatisation

Catherine Weetman, Michael S. Hill, Mary F. Mahon

Research output: Contribution to journalArticle

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Abstract

A kinetic analysis of the hydroboration of iso-quinoline with pinacol borane (HBpin) and catalysed by a β-diketiminato magnesium n-butyl pre-catalyst has provided evidence that the reaction proceeds via rate determining Mg–N/H–B metathesis of a dearomatised iso-quinolide anion. The reaction rate is suppressed by increasing [iso-quinoline] leading to the suggestion that catalytic turnover is also dependent on a pre-equilibrium involving dissociation of donor substrate molecules from the coordination sphere of the catalytic Mg centre. Stoichiometric reactions with a variety of poly-pyridine heterocycles have provided a range of magnesium derivatives of the dearomatised poly-pyridides either by alkyl or hydride transfer. The resistance of these latter species toward hydroboration is rationalised as a consequence of their additional coordinative stability providing corroborative evidence for the dissociative mechanism inferred from the kinetic analysis.
LanguageEnglish
Pages115-120
JournalPolyhedron
Volume103
Issue numberPart 8
Early online date31 Aug 2015
DOIs
StatusPublished - 8 Jan 2016

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hydroboration
Pyridines
quinoline
Pyridine
Magnesium
magnesium
pyridines
Boranes
Kinetics
boranes
metathesis
kinetics
Hydrides
hydrides
Reaction rates
suggestion
Anions
reaction kinetics
Negative ions
dissociation

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Magnesium-catalysed hydroboration of pyridines : kinetic analysis and poly-pyridine dearomatisation. / Weetman, Catherine; Hill, Michael S.; Mahon, Mary F.

In: Polyhedron, Vol. 103, No. Part 8, 08.01.2016, p. 115-120.

Research output: Contribution to journalArticle

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