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.
LanguageEnglish
Pages8567-8571
Number of pages4
JournalTetrahedron
Volume56
Issue number43
DOIs
Publication statusPublished - 20 Oct 2000

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Benzothiazoles
Benzoxazoles
Dealkylation
Amines
Substitution reactions
Iodides
Acetone
Chlorides
Derivatives

Keywords

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

Cite this

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title = "Unexpected Dealkylation During Nucleophilic Substitution: Synthesis of 2-N,N-Dialkylamino Benzoxazoles and Benzothiazoles",
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.",
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Unexpected Dealkylation During Nucleophilic Substitution: Synthesis of 2-N,N-Dialkylamino Benzoxazoles and Benzothiazoles. / Khalaf, A.I.; Alvarez, R.G.; Suckling, C.J.; Waigh, R.D.

In: Tetrahedron, Vol. 56, No. 43, 20.10.2000, p. 8567-8571.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Unexpected Dealkylation During Nucleophilic Substitution: Synthesis of 2-N,N-Dialkylamino Benzoxazoles and Benzothiazoles

AU - Khalaf, A.I.

AU - Alvarez, R.G.

AU - Suckling, C.J.

AU - Waigh, R.D.

PY - 2000/10/20

Y1 - 2000/10/20

N2 - 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.

AB - 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.

KW - 2-arylaminobenzoxazoles

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KW - 2-chlorobenzothiazole

KW - dealkylation

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KW - 3]diazepino[2

KW - 1-b][1

KW - 3]benzazoles

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