title: [4 + 2] Cyclocondensation reactions of tungsten-dihydropyridine complexes and the generation of tri- and tetrasubstituted piperidines.
abstract: A new method for the preparation of functionalized piperidines is described in which various dihydropyridine (DHP) complexes of {TpW(NO)(PMe(3))} that are derived from pyridine-borane undergo [4 + 2] cyclocondensation with enones, enals, nitrosobenzene, and several isocyanates to form [2.2.2] bicyclic species. In several cases the diazabicyclooctene products derived from DHP complexes and isocyanates can be further elaborated into novel syn-2,5-disubstituted and 2,3,6-trisubstituted piperidinamides.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Harrison
authors.forename: Diana A
authors.initials: DA
authors.lastname: Iovan
authors.forename: William H
authors.initials: WH
authors.lastname: Myers
authors.forename: Michal
authors.initials: M
authors.lastname: Sabat
authors.forename: Sisi
authors.initials: S
authors.lastname: Wang
authors.forename: Victor E
authors.initials: VE
authors.lastname: Zottig
authors.forename: W Dean
authors.initials: WD
authors.lastname: Harman
mesh_terms: D003500:Cyclization; D004095:Dihydropyridines / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010880:Piperidines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D014414:Tungsten / Q000737:chemistry*
chemical_list: D004095:Dihydropyridines; D009942:Organometallic Compounds; D010880:Piperidines; C038806:1,4-dihydropyridine; D014414:Tungsten