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Dalton Transactions

The international journal for inorganic, organometallic and bioinorganic chemistry



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Dalton Trans., 2010, 39, 641 - 653, DOI: 10.1039/b911851a

Bis(oxazolinyl)phenylborane: A Lewis acid-containing ligand for methide abstraction-based coordination to aluminum(III)

James F. Dunne, Kuntal Manna, Jerzy W. Wiench, Arkady Ellern, Marek Pruski and Aaron D. Sadow

A compound that contains a Lewis acidic boron center and coordinating oxazoline groups, bis(4,4-dimethyl-2-oxazolinyl)phenylborane (PhB(OxMe2)2; 1), has been prepared and spectroscopically characterized. Solvent dependent 15N and 11B NMR spectroscopic properties and solid-state 11B NMR measurements provide support for intermolecular interactions involving Lewis acid and base sites. The bifunctional nature of oxazolinylborane 1 is demonstrated by its reaction with (AlMe3)2, which proceeds via methide abstraction by the boron and oxazoline coordination to aluminum to yield [(2-PhMeB(OxMe2)2AlMe2] ( 2). Compound 2 contains a planar six-membered chelate ring, in contrast to related bis(pyrazolyl)boratoaluminum compounds that are puckered. Additionally, compound 2 and related bidentate tris(oxazolinyl)phenylborato dimethylaluminum are inert toward aluminum-methyl bond protonolysis. This robust nature suggested the possibility of using these oxazolinylboratoaluminum compounds in catalytic reactions, as is demonstrated by lactide ring-opening polymerization.

Graphical abstract image for this article (ID: b911851a)