title: Intramolecular ketene-allene cycloadditions.
abstract: [reaction: see text]This report describes intramolecular thermal [2 + 2] cycloadditions between ketenes and allenes. The formation of ketenes and the subsequent cycloadditions occurred under a variety of conditions, affording 7-methylidinebicyclo[3.2.0]heptanones and 7-methylidinebicyclo[3.1.1]heptanones in 45-78% yields. The regioselectivity of the cycloaddition varied with the substitution of the allene, and the yield of cyclized products varied with reaction conditions.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: McCaleb
authors.forename: R L
authors.initials: RL
authors.lastname: Halcomb
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis*; D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis*; D003500:Cyclization; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D001643:Bridged Bicyclo Compounds; D007202:Indicators and Reagents