Intramolecular Cyclization of Alkylhydroxylamines in Acids

抄録

Alkylhydroxylamines having a benzene ring in the molecule were subjected to intramolecular cyclization in trifluoroacetic acid or in the presence of Lewis acids, and benzenefused six-membered heterocycles were obtained in moderate yields from the cyclization reaction of O-acylhydroxylamines. The effect of a methoxyl group on the benzene ring was also investigated. The m-methoxy compound (1j) cyclized to give 6-methoxy-2-methyl-1, 2, 3, 4-tetrahydroquinoline (2e), while the p-methoxy compound (1k or 1l) cyclized to give the same product (2e). These unusual results could be explained in terms of a spiro-intermediate (3a).