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

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 dealky...

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Bibliographic Details
Published in:Tetrahedron 2000-10, Vol.56 (43), p.8567-8571
Main Authors: Khalaf, Abedawn I, Alvarez, Ricardo G, Suckling, Colin J, Waigh, Roger D
Format: Article
Language:English
Subjects:
2-arylaminobenzoxazoles
2-chlorobenzothiazole
2-chlorobenzoxazole
[1,3]diazepino[2,1-b][1,3]benzazoles
dealkylation
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Summary: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 1 H,2 H,3 H,4 H,5 H-[1,3]diazepino[2,1- b][1,3]benzoxazol-6-ium ring system.
ISSN:0040-4020
1464-5416
DOI:10.1016/S0040-4020(00)00802-4