Title

Rate-Limiting Step of the Rh-Catalyzed Carboacylation of Alkenes: C–C Bond Activation or Migratory Insertion?

Document Type

Article

Publication Date

1-11-2012

Publication Source

Journal of the American Chemical Society

Volume Number

134

Issue Number

1

First Page

715

Last Page

722

Publisher

American Chemical Society

ISSN

0002-7863

Abstract

Rhodium-catalyzed intramolecular carboacylation of alkenes, achieved using quinolinyl ketones containing tethered alkenes, proceeds via the activation and functionalization of a carbon-carbon single bond. This transformation has been demonstrated using RhCl(PPh3)(3) and [Rh(C2H4)(2)Cl](2) catalysts. Mechanistic investigations of these systems, including determination of the rate law and kinetic isotope effects, were utilized to identify a change in mechanism with substrate. With each catalyst, the transformation occurs via rate-limiting carbon-carbon bond activation for species with minimal alkene substitution, but alkene insertion becomes rate-limiting for more sterically encumbered substrates. Hammett studies and analysis of a series of substituted analogues provide additional insight into the nature of these turnover-limiting elementary steps of catalysis and the relative energies of the carbon-carbon bond activation and alkene insertion steps.

Keywords

CARBON-CARBON BOND, CROSS-COUPLING REACTIONS, H ACTIVATION, HOMOALLYL ALCOHOLS, SINGLE BOND, ALPHA, ALPHA-DISUBSTITUTED ARYLMETHANOLS, ORGANOMETALLIC CHEMISTRY, REDUCTIVE ELIMINATION, ASYMMETRIC ARYLATION, UNACTIVATED OLEFINS

COinS