Structure of Reaction Products of 5-Nitrosotropolone and Arylamine

Article abstract of DOI:10.1246/bcsj.63.3089

The structures of abnormal reaction products (1:1 and 1:2) between 5-nitrosotropolone and arylamine are elucidated.The reaction of 5-nitrosotropolone with arylamine (e.g., aniline and p-toluidine) affords initially a bicyclic addition product, having 8-azabicyclo<3.2.1>octane system which could be formed by the attack of the amine on 4- and 1-positions of the tropolone ring.The adduct contains two isomers having syn and anti configuration with respect to the hydroxyimino group.These adducts easily isomerized under alkaline conditions to form lactams having the 6-azabicyclo <3.2.1>octane system, which may have been resulted from skeletal rearrangement of a seven-membered ring to a six-membered one.The former adducts, the 8-azabicyclo<3.2.1>octane system, further react with another mole of arylamine to give 1:2 products containing a lactam moiety via similar skeletal rearrangement.