Dimerizations of 2-bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone in tetra-n-butylammonium bromide

Mai Onuki, Motohiro Ota, Shoya Otokozawa, Shogo Kamo, Shusuke Tomoshige, Kazunori Tsubaki, Kouji Kuramochi

Research output: Contribution to journalArticle

Abstract

2-Bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone are highly reactive species known to dimerize in various ways. The product obtained in the dimerization of each compound is primarily dependent upon the solvent used. Ionic liquids represent a new class of solvents having non-molecular (ionic) character. Replacement of a conventional organic solvent with an ionic solvent frequently changes the mechanism of a reaction. In this study, reactions of 2-bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone in ionic liquids were examined. Dimerization of 2-bromo-3-methyl-1,4-naphthoquinone or 2-methyl-1,4-naphthoquinone with N-methylcyclohexylamine in tetra-n-butylammonium bromide (TBAB), an ionic liquid, under an aerobic atmosphere afforded 5,7,12,14-pentacenetetrone and 1-methylKuQuinone, respectively. The use of TBAB as a solvent improved the yields of the products as compared with previously reported methods. The mechanism of each dimerization was also investigated.

Original languageEnglish
Article number130899
JournalTetrahedron
Volume76
Issue number6
DOIs
Publication statusPublished - 2020 Feb 7
Externally publishedYes

Keywords

  • 1,4-Naphthoquinone
  • 1-MethylKuQuinone
  • 5,7,12,14-Pentacenetetrone
  • Dimerization
  • Ionic liquid

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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