title: Rearrangements of cyclobutenones. Electrocyclic ring closure and thermal ring expansions of 3-allenyl- and 3-alkynyl-2-dienyl-4,4-dimethoxycyclobutenones.
abstract: Thermal rearrangements of 2-allenyl- and 2-alkynyl-3-(2-ethenylphenyl)-4,4-dimethoxycyclobutenones were studied. At ambient temperature, the allenyl compounds undergo an electrocyclic cascade to give bicyclo[4.2.0]octadienyl-fused cyclobutenones. These unusual tetracyclic cyclobutenones were shown to be viable synthetic precursors to benzo[a]anthracene-7,12-diones, compounds representing the framework of the angucycline group of naturally occurring antibiotics. In contrast, the 2-alkynylcyclobutenones are stable at ambient temperature but undergo a facile rearrangement at 110 degrees C (toluene) to give the previously unknown naphthalene derivatives, 1,2-dihydro-2,2-dimethoxy-1-(3-alkenylidene)naphtho[2,1-b]furans.
authors.affiliation: Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Hergueta
authors.forename: Harold W
authors.initials: HW
authors.lastname: Moore
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D002384:Catalysis; D002855:Chromatography, Thin Layer; D018360:Crystallography, X-Ray; D003500:Cyclization; D003503:Cyclobutanes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008697:Methane / Q000031:analogs & derivatives / Q000737:chemistry; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013696:Temperature; D014050:Toluene / Q000737:chemistry
chemical_list: D001555:Benzene Derivatives; D003503:Cyclobutanes; D014050:Toluene; D008697:Methane