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Relative reactivity of alkenyl alcohols in the palladium-catalyzed redox-relay Heck reaction

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posted on 26.05.2016, 11:36 by Margaret J. Hilton, Bin Cheng, Benjamin BuckleyBenjamin Buckley, Liping Xu, Olaf Wiest, Matthew S. Sigman
The relative rates of alkenyl alcohols in the Pd-catalyzed redox-relay Heck reaction were measured in order to examine the effect of their steric and electronic properties on the rate-determining step. Competition experiments between an allylic alkenyl alcohol and two substrates with differing chain lengths revealed that the allylic alcohol reacts 3–4 times faster in either case. Competition between di- and trisubstituted alkenyl alcohols provided an interesting scenario, in which the disubstituted alkene was consumed first followed by reaction of the trisubstituted alkene. Consistent with this observation, the transition structures for the migratory insertion of the aryl group into the di- and trisubstituted alkenes were calculated with a lower barrier for the former. An internal competition between a substrate containing two alcohols with differing chain lengths demonstrated the catalyst's preference for migrating toward the closest alcohol. Additionally, it was observed that increasing the electron-density in the arene boronic acid promotes a faster reaction, which correlates with Hammett [sigma-rho] values to give a [rho] of −0.87.

Funding

BRB would like to thank Loughborough University for study leave funding.

History

School

  • Science

Department

  • Chemistry

Published in

TETRAHEDRON

Volume

71

Issue

37

Pages

6513 - 6518 (6)

Citation

HILTON, M. ... et al., 2015. Relative reactivity of alkenyl alcohols in the palladium-catalyzed redox-relay Heck reaction. Tetrahedron, 71 (37), pp.6513-6518.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2015

Notes

This paper was accepted for publication in the journal Tetrahedron and the definitive published version is available at http://dx.doi.org/10.1016/j.tet.2015.05.020

ISSN

0040-4020

Language

en