title: Sulfonamides as novel terminators of cationic cyclisations.
abstract: Trifluoromethanesulfonic (triflic) acid is an excellent catalyst for inducing overall 5-endo cyclisation of homoallylic sulfonamides [e.g. 4] to give pyrrolidines [e.g. 5]. In competitive experiments, pyrrolidines or homopiperidines are formed in preference to piperidines, even when the latter would be obtained by trapping a tertiary carbocation. Cationic cascades terminated by a sulfonamide group are viable for the efficient formation of polycyclic systems.
authors.affiliation: Chemistry Department, Cardiff University, P.O. Box 912, Cardiff, UK CF10 3TB.
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Haskins
authors.forename: David W
authors.initials: DW
authors.lastname: Knight