Formation of 2-bromo-4-t-butyl-7-methoxy-2H-azepine and 4-t-butyl-7-methoxy-2-succinimidyl-2H-azepine by the respective reactions of 5-t-butyl-2-methoxy-3H-azepine with bromine and NBS suggests a plausible mechanism for the conversion of 3H-azepine to 2H-azepine as 1,4-addition of an electrophile and a consequent 1,2-dehydrobromination. Different from the case of cycloheptatriene, reaction of 3H-azepine with bromine did not give any delocalized ionic species.
Reaction of 2-Methoxy-3<i>H</i>-azepine with NBS: Efficient Synthesis of 2-Substituted 2<i>H</i>-Azepines
作者:Christopher E. J. Cordonier、Kyosuke Satake、Mikihiko Atarashi、Yousuke Kawamoto、Hideki Okamoto、Masaru Kimura
DOI:10.1021/jo0500232
日期:2005.4.1
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