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

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

Research output: Contribution to journalArticle

109 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)1840-1858
Number of pages19
JournalJournal of the American Chemical Society
Volume119
Issue number8
DOIs
StatePublished - Feb 26 1997
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Nelson, D. W., Gypser, A., Ho, P. T., Kolb, H. C., Kondo, T., Kwong, H. L., McGrath, D. V., Rubin, A. E., Norrby, P. O., Gable, K. P., & Sharpless, K. B. (1997). Toward an understanding of the high enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation. 4. Electronic effects in amine-accelerated osmylations. Journal of the American Chemical Society, 119(8), 1840-1858. https://doi.org/10.1021/ja961464t