Bond-Weakening Catalysis: Conjugate Aminations Enabled by the Soft Homolysis of Strong N-H Bonds

Kyle T. Tarantino, David C. Miller, Ted A. Callon, Robert R. Knowles

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

The ability of redox-active metal centers to weaken the bonds in associated ligands is well precedented, but has rarely been utilized as a mechanism of substrate activation in catalysis. Here we describe a catalytic bond-weakening protocol for conjugate amination wherein the strong N-H bonds in N-aryl amides (N-H bond dissociation free energies ∼100 kcal/mol) are destabilized by ∼33 kcal/mol upon by coordination to a reducing titanocene complex, enabling their abstraction by the weak H-atom acceptor TEMPO through a proton-coupled electron transfer process. Significantly, this soft homolysis mechanism provides a method to generate closed-shell, metalated nucleophiles under neutral conditions in the absence of a Bronsted base.

Original languageEnglish (US)
Pages (from-to)6440-6443
Number of pages4
JournalJournal of the American Chemical Society
Volume137
Issue number20
DOIs
StatePublished - May 27 2015

All Science Journal Classification (ASJC) codes

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

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