The allyl intermediate in regioselective and enantioselective iridium-catalyzed asymmetric allylic substitution reactions

Sherzod Madrahimov, Dean Markovic, John F. Hartwig

Research output: Contribution to journalArticle

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Abstract

(Chemical Equation Presented) The isolation and structural characterization of metallacyclic allyl (2a) and crotyl (2b) iridium complexes are reported. Complexes 2a and 2b are rare examples of iriduim allyl complexes that undergo nucleophilic attack at terminal position, rather than the central position, of the allyl unit. Structures of 2a and 2b were obtained by X-ray diffraction. Nucleophilic attack was observed at the carbon that is bound to iridium trans to phosphorus through a longer Ir-C bond. However, the effect of the trans phosphine ligand on the Ir-C bond lengths was smaller than the effect of the substituent on the allyl group in 2b. The competence of complexes 2a and 2b to be intermediates in the catalytic asymmetric allylic substitutions was evaluated by studying their reactivity toward stabilized carbon and heteroatom nucleophiles and comparing the rates and selectivities to those of the catalytic reactions. The stereoselectivity and regioselectivity of stoichiometric reactions of 2b were similar to those of reactions catalyzed by the previously reported iridium catalysts, supporting their intermediacy in the catalytic reactions. On the basis of the structural data, a model is proposed for the origin of stereoselectivity in iridium-catalyzed asymmetric allylic substitution reactions.

Original languageEnglish
Pages (from-to)7228-7229
Number of pages2
JournalJournal of the American Chemical Society
Volume131
Issue number21
DOIs
Publication statusPublished - 3 Jun 2009
Externally publishedYes

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Iridium
Substitution reactions
Stereoselectivity
phosphine
Carbon
Regioselectivity
Nucleophiles
Bond length
X-Ray Diffraction
Mental Competency
Phosphorus
Ligands
X ray diffraction
Catalysts

ASJC Scopus subject areas

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

Cite this

The allyl intermediate in regioselective and enantioselective iridium-catalyzed asymmetric allylic substitution reactions. / Madrahimov, Sherzod; Markovic, Dean; Hartwig, John F.

In: Journal of the American Chemical Society, Vol. 131, No. 21, 03.06.2009, p. 7228-7229.

Research output: Contribution to journalArticle

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