Unexpected Dealkylation During Nucleophilic Substitution: Synthesis of 2-N,N-Dialkylamino Benzoxazoles and Benzothiazoles

A.I. Khalaf, R.G. Alvarez, C.J. Suckling, R.D. Waigh

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Mild reaction conditions are described for the preparation of a number of 2-alkyl- and 2-arylaminobenzoxazoles and benzothiazoles from 2-chlorobenzoxazole and 2-chlorobenzothiazole and N-methyl or other simple N-alkyl tertiary amines. The reaction proceeds neat or in THF solution and involves dealkylation of the amine reactant by nucleophilic substitution by chloride. In the case of N-methylpyrrolidine and N-methylpiperidine demethylation was not observed and the major product was formed by ring opening to give chlorobutyl- and chloropentyl-methylamino substituted benzoxazoles and benzothiazoles. Treatment of the chlorobutyl derivative with iodide in acetone afforded the new 1H,2H,3H,4H,5H-[1,3]diazepino[2,1-b][1,3]benzoxazol-6-ium ring system.
Original languageEnglish
Pages (from-to)8567-8571
Number of pages4
JournalTetrahedron
Volume56
Issue number43
DOIs
Publication statusPublished - 20 Oct 2000

Keywords

  • 2-arylaminobenzoxazoles
  • 2-chlorobenzoxazole
  • 2-chlorobenzothiazole
  • dealkylation
  • [1
  • 3]diazepino[2
  • 1-b][1
  • 3]benzazoles

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