title: Reaction of 2-methoxy-3H-azepine with NBS: efficient synthesis of 2-substituted 2H-azepines.
abstract: [reaction: see text] The reaction of 2-methoxy-3H-azepines, in the presence or absence of a nucleophile, with N-bromosuccinimide (NBS) gave a regioselective 1,4-adduct from which the corresponding 2H-azepine derivatives were formed via base-promoted hydrogen bromide elimination, generally in moderate to quantitative yield. Competitive formation of 4-bromo-2-methoxy-3H-azepine by electrophilic substitutuion or 3H-azepin-2-yl 2H-azepin-2-yl ether by transetherification was minimized at lower reaction temperatures. Quantitative substitution of 2-(2',4',6'-trichlorophenoxy)-2H-azepine derivatives, formed in moderate yield from the respective 3H-azepine and NBS in the presence of 2,4,6-trichlorophenol (TCP), by various nucleophiles gave the corresponding 2-substituted 2H-azepine. Among these nucleophiles were alkanethiol and alkylamine that are not tolerated in the reaction of 3H-azepine and NBS.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, Tsushima-Naka 3-1-1, Okayama 700-8530, Japan.
authors.forename: Christopher E J
authors.initials: CE
authors.lastname: Cordonier
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Satake
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Atarashi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Kawamoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Okamoto
authors.forename: Masaru
authors.initials: M
authors.lastname: Kimura