Kyosuke Satake, Yuko Tawada, Hideki Okamoto and Masaru Kimura
The selective formation of 2-methoxy-2H-azepine from 3H-azepines, via a likely azatropylium cation, is reported; the first isolation of 2-azanorcaradiene, which is considered to be the valence isomer of 3H-azepine, is also described.