title: The profound effect of the ring size in the electrocyclic opening of cyclobutene-fused bicyclic systems.
abstract: Fused cyclobutenes, prepared by the photocycloaddition of propargyl alcohols to cyclic anhydride chromophores, undergo facile thermochemical ring opening to fused γ-lactones. The size of the fused ring profoundly influences the temperature that is required to facilitate the ring opening (from 50 °C to 180 °C) and the nature of the product that is formed. Our studies provide new insights into the mechanistic course of these reactions and have been extended to facilitate the preparation of lactams fused to medium-sized rings.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS (UK) http://www.chm.bris.ac.uk/org/bmilburn/index2.htm.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ralph
authors.forename: David C
authors.initials: DC
authors.lastname: Harrowven
authors.forename: Steven
authors.initials: S
authors.lastname: Gaulier
authors.forename: Sean
authors.initials: S
authors.lastname: Ng
authors.forename: Kevin I
authors.initials: KI
authors.lastname: Booker-Milburn
mesh_terms: D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D003503:Cyclobutanes / Q000737:chemistry*; D007769:Lactams / Q000138:chemical synthesis / Q000737:chemistry; D055668:Photochemical Processes; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D001643:Bridged Bicyclo Compounds; D003503:Cyclobutanes; D007769:Lactams
keywords: cyclobutenes; electrocyclic reactions; fused-ring systems; photochemistry; ring opening