A new route to cycloheptatrienylideneammonium salts; restricted rotation about the CN bond

Abstract

Reactions of 3- and 4-dimethylaminocycloheptatrienone with methyl flurosulphate and the reaction of the 3-derivative with methyl iodide result in predominant O-methylation. The N-methyl groups of the 4-methoxy-salt (4) are magnetically non-equivalent at room temperature, but the corresponding methyl groups of the 2- and 3-isomers are indistinguishable, even at –80°C.