title: Radical cascade transformations of tris(o-aryleneethynylenes) into substituted benzo[a]indeno[2,1-c]fluorenes.
abstract: Oligomeric o-aryleneethynylenes with three triple bonds undergo cascade radical transformations in reaction with a Bu 3SnH/AIBN system. These cascades involve three consecutive cycle closures with the formation of substituted benzo[ a]indeno[2,1- c]fluorene or benzo[1,2]fluoreno[4,3- b]silole derivatives. The success of this sequence depends on regioselectivity of the initial attack of the Bu 3Sn radical at the central triple bond of the o-aryleneethynylene moiety. The cascade is propagated through the sequence of 5-exo-dig and 6-exo-dig cyclizations which is followed by either a radical attack at the terminal Ar substituent or radical transposition which involves H-abstraction from the terminal TMS group and 5-endo-trig cyclization. Overall, the transformation has potential to be developed into an approach to a new type of graphite ribbons.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, USA. alabugin@chem.fsu.edu
authors.forename: Igor V
authors.initials: IV
authors.lastname: Alabugin
authors.forename: Kerry
authors.initials: K
authors.lastname: Gilmore
authors.forename: Satish
authors.initials: S
authors.lastname: Patil
authors.forename: Mariappan
authors.initials: M
authors.lastname: Manoharan
authors.forename: Serguei V
authors.initials: SV
authors.lastname: Kovalenko
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Clark
authors.forename: Ion
authors.initials: I
authors.lastname: Ghiviriga
mesh_terms: D000465:Algorithms; D000480:Alkynes / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D003500:Cyclization; D004987:Ethers / Q000737:chemistry*; D005449:Fluorenes / Q000138:chemical synthesis*; D005609:Free Radicals / Q000737:chemistry*; D007192:Indenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000480:Alkynes; D001555:Benzene Derivatives; D004987:Ethers; D005449:Fluorenes; D005609:Free Radicals; D007192:Indenes; C436384:phenyleneethynylene