Me2AlCl-mediated carboxylation, ethoxycarbonylation, and carbamoylation of indoles

Koji Nemoto, Shinya Tanaka, Megumi Konno, Satoru Onozawa, Masafumi Chiba, Yuuki Tanaka, Yosuke Sasaki, Ryo Okubo, Tetsutaro Hattori

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

Various 1-methyl-, 1-triisopropylsilyl-, and 1-benzylindoles are carboxylated under CO2 pressure (3.0 MPa) with the aid of 1.0 molar equiv of Me2AlCl to give 1-substituted indole-3-carboxylic acids in good to excellent yields. Mechanistic studies suggest that the intermediate, an indol-3-ylaluminum ate complex, was reversibly formed by electrophilic addition of Me2AlCl to the substrate followed by deprotonation of the resulting adduct. This method is successfully extended to alkoxycarbonylation with ethyl chloroformate and carbamoylation with naphthalen-1-yl isocyanate, which afford ethyl indole-3-carboxylates and N-naphthalen-1-ylindole-3-carboxamides, respectively.

Original languageEnglish
Pages (from-to)734-745
Number of pages12
JournalTetrahedron
Volume72
Issue number5
DOIs
Publication statusPublished - 2016 Feb 4

Keywords

  • Alkoxycarbonylation
  • Alumination
  • Carbamoylation
  • Carboxylation
  • Indole

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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