title: Pyridines from azabicyclo[3.2.0]hept-2-en-4-ones through a proposed azacyclopentadienone.
abstract: Pyridines have been formed by heating azabicyclo[3.2.0]hept-2-en-4-ones in toluene. The generation of a 3-azacyclopentadienone intermediate via a [2 + 2]-cycloreversion is proposed as the key step. A Diels-Alder reaction of a styrene, extrusion of carbon monoxide, and loss of hydrogen then gives the pyridine. The process parallels the well-known synthesis of benzenes from cyclopentadienones. The azabicyclo[3.2.0]hept-2-en-4-ones were synthesized from the reaction between readily available cyclopropenones and 1-azetines, in which the cyclopropenones behave as all-carbon 1,3-dipolar equivalents.
authors.affiliation: Institute for Materials, Medicines and Molecular Sciences, Division of Chemistry, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire, HD1 3DH, United Kingdom. k.hemming@hud.ac.uk
authors.forename: Karl
authors.initials: K
authors.lastname: Hemming
authors.forename: Musharraf N
authors.initials: MN
authors.lastname: Khan
authors.forename: Vishnu V R
authors.initials: VV
authors.lastname: Kondakal
authors.forename: Arnaud
authors.initials: A
authors.lastname: Pitard
authors.forename: M Ilyas
authors.initials: MI
authors.lastname: Qamar
authors.forename: Craig R
authors.initials: CR
authors.lastname: Rice
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D053961:Azabicyclo Compounds / Q000737:chemistry*; D015394:Molecular Structure; D011725:Pyridines / Q000138:chemical synthesis*
chemical_list: D000466:Alkadienes; D053961:Azabicyclo Compounds; D011725:Pyridines