title: Synthesis of oligoenes that contain up to 15 double bonds from 1,6-heptadiynes.
abstract: This paper reports the synthesis of polyene oligomers ("oligoenes") that contain up to 15 double bonds that are identical to the "all five-membered ring" species formed through cyclopolymerization of diisopropyldipropargylmalonate. The oligoenes contain an isopropylidene unit at each end. The isolated oligoenes range from the "dimer" (a pentaene, (E)-di-1,2-[1-(2-methyl-propenyl)-4,4-di-iso-propyl-carboxy-cyclopent-1-enyl]-ethene (3b2)) to the "heptamer" (3b7, a pentadecaene). Oligoenes 3b2, 3b3, 3b4, 3b5, and 3b7 were prepared through Wittig-like reactions between aldehydes and the appropriate monometallic Mo alkylidene or bimetallic Mo bisalkylidene species whose alkylidene is derived from an identical five-membered ring monomeric unit. Compounds 3b2, 3b4, and 3b6 were prepared through McMurry coupling reactions of aldehydes. A representative aldehyde (the "monomeric" aldehyde) is diisopropyl-3-formyl-4-(2-methylprop-1-enyl)cyclopent-3-ene-1,1-dicarboxylate (2b), McMurry coupling of which yields 3b2. A heptaene that contains a six-membered ring in the central unit also was prepared in a Wittig-like reaction involving a bimetallic Mo alkylidene; this species is a model for oligoenes that contain both six-membered and five-membered rings. X-ray structures of two bimetallic species that are employed in the synthesis of the oligoenes are reported.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Constantin
authors.initials: C
authors.lastname: Czekelius
authors.forename: Jillian
authors.initials: J
authors.lastname: Hafer
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Tonzetich
authors.forename: Richard R
authors.initials: RR
authors.lastname: Schrock
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Christensen
authors.forename: Peter
authors.initials: P
authors.lastname: Müller
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011090:Polyenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D009942:Organometallic Compounds; D011090:Polyenes; D008982:Molybdenum