Tuesday, June 19, 2007 - 1:05 PM
The Merlins (Boise Centre on the Grove)

Ligand-based control of thermodynamics in alkene/diolate interconversion

Kevin P. Gable, Joshua Albus, and Abigail Joyce. Oregon State University, Corvallis, OR

Cycloaddition of strained and unstrained alkenes to cationic rhenium oxo complexes LReO3+ occurs in acetonitrile at temperatures above 80 C. (L = tris-(3,5-dimethylpyrazolyl)methane.) Equilibrium constants vary from a low of 1.6 for styrene to 11 for Z-cyclooctene to >200 for norbornene. These results are consistent with computational modeling in comparison with the chemistry of neutral tris-pyrazolylborate complexes. Initial exploration indicates tolerance of several functional groups, and variation of Keq with electronic properties of the alkene, as expected. This ligand control opens opportunities for further modification of the ligand for imposing aspects of regio- and stereocontrol of atom transfer reactions.