title: [4 + 2] cycloadditions of N-alkenyl iminium ions: structurally complex heterocycles from a three-component Diels-Alder reaction sequence.
abstract: N-Alkenyl iminium ions serve as conduits to three-component [4 + 2] cycloaddition reactions accessing structurally and stereochemically diverse piperidine derivatives. These cationic 2-azadienes participate in endo- or exo-selective [4 + 2] cycloadditions with electron-rich and neutral alkene dienophiles to generate a tetrahydropyridinium ion as the initial cycloadduct. In situ nucleophilic addition to the cycloaddition-derived iminium ion completes the three-component coupling sequence and affords a versatile synthesis of structurally complex piperidines.
authors.affiliation: University of Pittsburgh Center for Chemical Methodologies and Library Development, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Nihar
authors.initials: N
authors.lastname: Sarkar
authors.forename: Abhisek
authors.initials: A
authors.lastname: Banerjee
authors.forename: Scott G
authors.initials: SG
authors.lastname: Nelson
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D007097:Imines / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D010880:Piperidines / Q000138:chemical synthesis*
chemical_list: D000475:Alkenes; D007097:Imines; D007211:Indoles; D010880:Piperidines