Mechanistic Insights into Rhenium-Catalyzed Regioselective C-Alkenylation of Phenols with Internal Alkynes

Masahito Murai, Masaki Yamamoto, Kazuhiko Takai

Research output: Contribution to journalArticle

Abstract

A (μ-aryloxo)rhenium complex was isolated and confirmed as a key precatalyst for rhenium-catalyzed ortho-alkenylation (C-alkenylation) of unprotected phenols with alkynes. The reaction exclusively provided ortho-alkenylphenols; the formation of para or multiply alkenylated phenols and hydrophenoxylation (O-alkenylation) products was not observed. Several mechanistic experiments excluded a classical Friedel–Crafts-type mechanism, leading to the proposed phenolic hydroxyl group assisted electrophilic alkenylation as the most plausible reaction mechanism. For this purpose, the use of rhenium, a metal between the early and late transition metals in the periodic table, was key for the activation of both the soft carbon–carbon triple bond of the alkyne and the hard oxygen atom of the phenol, at the same time. ortho-Selective alkenylation with allenes also provided the corresponding adducts with a substitution pattern different from that obtained by the addition reaction with alkynes.

Original languageEnglish
JournalChemistry - A European Journal
DOIs
Publication statusAccepted/In press - Jan 1 2019

Fingerprint

Alkenylation
Rhenium
Alkynes
Phenols
Addition reactions
Phenol
Hydroxyl Radical
Transition metals
Substitution reactions
Metals
Chemical activation
Oxygen
Atoms
Experiments

Keywords

  • alkenylation
  • homogeneous catalysis
  • reaction mechanisms
  • regioselectivity
  • rhenium

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

Cite this

Mechanistic Insights into Rhenium-Catalyzed Regioselective C-Alkenylation of Phenols with Internal Alkynes. / Murai, Masahito; Yamamoto, Masaki; Takai, Kazuhiko.

In: Chemistry - A European Journal, 01.01.2019.

Research output: Contribution to journalArticle

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