Important consequences for gas chromatographic analysis of the Sonogashira cross-coupling reaction

GC analysis of the Sonogashira reaction of 1 with phenylacetylene shows a time dependence of post-quenched samples (through a conventional silica plug), where residual Pd complexes are able to catalyse the reaction further. On following the kinetics of the Sonogashira alkynylation reaction of haloge...

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Bibliographic Details
Published in:Tetrahedron letters 2004-04, Vol.45 (18), p.3593-3595
Main Authors: Niemelä, Elina H., Lee, Adam F., Fairlamb, Ian J.S.
Format: Article
Language:English
Subjects:
2-Pyrones
Cross-coupling reactions
Palladium
Sonogashira
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Summary:GC analysis of the Sonogashira reaction of 1 with phenylacetylene shows a time dependence of post-quenched samples (through a conventional silica plug), where residual Pd complexes are able to catalyse the reaction further. On following the kinetics of the Sonogashira alkynylation reaction of halogenated 2-pyrone 1 with phenylacetylene we have found that turnover continues to occur in sample vials even after quenching by commonly employed silica adsorption methods and product elution with small quantities of CH 2Cl 2. Trace quantities of Pd are carried through the silica plug. Addition of a CH 2Cl 2 solution of 1,2-bis(diphenylphosphino)ethane (dppe) to the quenched sample inhibits the reaction and represents a more reliable method for determining yields and reaction kinetics.
ISSN:0040-4039
1873-3581
DOI:10.1016/j.tetlet.2004.03.060