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

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• 作者：Khalaf ; Abedawn I. ; Alvarez ; Ricardo G. ; Suckling ; Colin J. ; Waigh ; Roger D.
• 关键词：2-arylaminobenzoxazoles ; 2-chlorobenzoxazole ; 2-chlorobenzothiazole ; dealkylation ; [1 ; 3]diazepino[2 ; 1-b][1 ; 3]benzazoles
• 刊名：Tetrahedron
• 出版年：2000
• 出版时间：October 20, 2000
• 年：2000
• 卷：56
• 期：43
• 页码：8567-8571
• 全文大小：98.5 K

文摘

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 <i>Ni>-methyl or other simple <i>Ni>-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 <i>Ni>-methylpyrrolidine and <i>Ni>-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<i>Hi>,2<i>Hi>,3<i>Hi>,4<i>Hi>,5<i>Hi>-[1,3]diazepino[2,1-<i>bi>][1,3]benzoxazol-6-ium ring system.