Catalytic, enantioselective, intramolecular carbosulfenylation of olefins. mechanistic aspects: A remarkable case of negative catalysis

Scott E. Denmark, Hyung Min Chi

Research output: Contribution to journalArticle

Abstract

In the course of developing an enantioselective, Lewis base/Brønsted acid co-catalyzed carbosulfenylation of alkenes, a seemingly impossible conundrum arose: How could a catalyst inhibit a stoichiometric reaction? Despite the observation of very good enantioselectivities, the rate of the uncatalyzed reaction (i.e., no Lewis base) was found to be comparable to or slightly faster than that of the catalyzed process. A combination of detailed kinetic and spectroscopic studies revealed that the answer is not the direct involvement of the Lewis base catalyst, but rather the secondary consequences of its conversion to the catalytically active sulfenylating agent. Generation of the chiral sulfenylating species is accompanied by the formation of equimolar amounts of sulfonate ion and phthalimide which serve to buffer the remaining Brønsted acid and thus inhibit the racemic background reaction. Thus, the actual background reaction operative under catalytic conditions is not well mimicked by simply removing the catalyst.

Original languageEnglish (US)
Pages (from-to)3655-3663
Number of pages9
JournalJournal of the American Chemical Society
Volume136
Issue number9
DOIs
StatePublished - Mar 5 2014

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ASJC Scopus subject areas

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

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