title: Lewis Acid Accelerated Aryl Ether Bond Cleavage with Nickel: Orders of Magnitude Rate Enhancement Using AlMe3.
abstract: Study of the kinetics of intramolecular aryl ether C-O bond cleavage by Ni was facilitated by access to a family of metal complexes supported by diphosphines with pendant aryl-methyl ethers. The nature of the aryl substituents was found to have little effect on the rate of cleavage. In contrast, soluble Lewis acidic additives accelerate the aryl ether cleavage dramatically. The effect of AlMe3was studied in detail, and showed an increase in rate by several orders of magnitude. Low temperature NMR spectroscopy studies demonstrate quantitative coordination of ether to Al. From the Lewis acid-bound precursor, the activation parameters for ether cleavage are significantly lower. These findings provide a mechanistic basis for milder catalyst design for the activation of strong bonds.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125 MC 127-72, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Kelley
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125 MC 127-72, USA.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Edouard
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125 MC 127-72, USA.
authors.forename: Sibo
authors.initials: S
authors.lastname: Lin
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125 MC 127-72, USA.
authors.forename: Theodor
authors.identifier: http://orcid.org/0000-0002-9692-7614
authors.initials: T
authors.lastname: Agapie
keywords: Lewis acid; aryl ether cleavage; cross coupling; nickel; rate acceleration