title: Studies dealing with thionium ion promoted mannich cyclization reactions.
abstract: Treatment of several amido-substituted thioacetals with dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) produces synthetically useful thionium ions that are intercepted by the adjacent nitrogen atom to afford both five- and six-membered alkylthio-substituted lactams as transient intermediates. Further reaction of the alkylthio-substituted lactam with DMTSF generates an N-acyliminium ion, which undergoes cyclization with the tethered aromatic ring to produce an azapolycyclic ring system. Related cyclization sequences occur when amido thioacetals possessing simple olefinic tethers were used. The overall procedure represents an efficient one-pot approach toward various nitrogen-containing ring systems. The cyclization reaction was employed for a synthesis of the core skeleton of the erythrina alkaloid family.
authors.affiliation: Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: A
authors.initials: A
authors.lastname: Padwa
authors.forename: A G
authors.initials: AG
authors.lastname: Waterson
mesh_terms: D004220:Disulfides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D004220:Disulfides; D000644:Quaternary Ammonium Compounds; C414104:dimethyl(methylthio)sulfonium; C059915:thionium