Toward an understanding of the high enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation. 4. Electronic effects in amine-accelerated osmylations

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

125 Scopus Citations
View graph of relations

Author(s)

  • Derek W. Nelson
  • Andreas Gypser
  • Pui Tong Ho
  • Hartmuth C. Kolb
  • Teruyuki Kondo
  • Dominic V. McGrath
  • A. Erik Rubin
  • Per-Ola Norrby
  • Kevin P. Gable
  • K. Barry Sharpless

Detail(s)

Original languageEnglish
Pages (from-to)1840-1858
Journal / PublicationJournal of the American Chemical Society
Volume119
Issue number8
Publication statusPublished - 26 Feb 1997
Externally publishedYes

Abstract

Electronic effects in osmylation reactions accelerated by pyridine and quinuclidine derivatives were investigated by varying the substituents on the amine ligand as well as on the alkene substrate. Ligand substituent effects were gauged by determination of the equilibrium constants for coordination of the amines to OsO4, evaluation of structural properties and reduction potentials of the amine-OsO4 complexes, and analysis of the kinetics of osmylations in the presence of the amines. Substrate substituent effects were gauged by kinetic Hammett studies using several different amine/alkene combinations. Nonlinear Hammett relationships resulting from alkene substituent effects were observed, and the deviation from a linear free energy relationship was found to depend on the structure, binding capacity, and concentration of the amine. The results were evaluated in terms of the contending '[3 + 2]' and '[2 + 2]' mechanisms currently under consideration. A change in mechanism that depends on the structural and electronic properties of both alkene and amine is proposed.

Citation Format(s)

Toward an understanding of the high enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation. 4. Electronic effects in amine-accelerated osmylations. / Nelson, Derek W.; Gypser, Andreas; Ho, Pui Tong et al.
In: Journal of the American Chemical Society, Vol. 119, No. 8, 26.02.1997, p. 1840-1858.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review