title: Theoretical studies on cycloaddition reactions between keteniminium cations and olefins.
abstract: The mechanisms of seven reactions between keteniminium cations and olefins have been theoretically explored at BHandHLYP/6-31G level. It is found that these seven reactions always form a relatively stable hydrogen-bonded type of ion-molecule complex first except for reactions 1d+2a and 1e+2a, which have no hydrogen atom attached to nitrogen atom in keteniminium cations. Some reactions take place via a concerted but unsynchronous mechanism, and the others are stepwise processes. The substituent effects are also studied. The data reveal that the electron-pushing substituents on keteniminium cations disfavor the reaction, and the electron-attracting substituents on keteniminium cations favor the reactions. The substituent effects on ethene are contrary to the former case.
authors.affiliation: Department of Chemistry, Beijing Normal University, 100875, People's Republic of China.
authors.forename: W J
authors.initials: WJ
authors.lastname: Ding
authors.forename: D C
authors.initials: DC
authors.lastname: Fang