Selectivity Switch in the Synthesis of Vinylgold(I) Intermediates

A. Stephen K. Hashmi, Andreas M. Schuster, Sylvain Gaillard, Luigi Cavallo, Albert Poater, Steven P. Nolan

Research output: Contribution to journalArticlepeer-review

110 Citations (Scopus)

Abstract

An unexpected regioselectivity reversal was observed in the synthesis of vinylgold(I) complexes from propargyl carboxamides. The use of [Au(IPr)(OH)] affords preferentially vinylgold(I) complexes resulting from a 5-exo-dig cyclization, whereas the use [Au(IPr)](+) species, generated in situ starting from [Au(IPr)(Cl)] and AgOTf, leads to vinylgold(I) complexes which form via a 6-endo-dig cyclization, This unexpected "selectivity switch" for this cyclization led us to propose two different reaction pathways enabling the formation of the two different products. One mechanism involves the [Au(IPr)](+) species with "classical" pi activation of the alkyne framework of the carboxamides, and the second represents an "unusual" use of the basic Bronsted character of [Au(IPr)(OH)). Mechanistic and DFT studies support the mechanistic hypotheses.

Original languageEnglish
Pages (from-to)6328-6337
Number of pages10
JournalOrganometallics
Volume30
Issue number22
Early online date28 Oct 2011
DOIs
Publication statusPublished - 28 Nov 2011

Keywords

  • HOMOGENEOUS GOLD CATALYSIS
  • N-HETEROCYCLIC CARBENE
  • C-H BONDS
  • STRUCTURAL-CHARACTERIZATION
  • PLATINUM CATALYSIS
  • SOLUTION BEHAVIOR
  • COMPLEXES
  • ALKYNES
  • HYDROAMINATION
  • ALLENES

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