title: Reversal of regioselectivity (straight vs. cross ring closure) in the intramolecular [2+2] photocycloaddition of phenanthrene derivatives.
abstract: Intramolecular [2+2] photocycloaddition of aromatic chain imides possessing bis-phenanthrene moieties afforded straight and cross ring closure products. The ratio of cycloadducts was dependent on reaction time and temperature, which resulted in a reversal of regioselectivity. The reaction was proved to involve a retro cycloaddition. The cross ring closure products were formed predominantly in the early stage of the reaction at lower reaction temperature. In contrast, the straight ring closure products were predominant at higher reaction temperature with prolonged irradiation.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. kohmoto@faculty.chiba-u.jp
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kohmoto
authors.forename: Shugo
authors.initials: S
authors.lastname: Hisamatsu
authors.forename: Hakuei
authors.initials: H
authors.lastname: Mitsuhashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hyuma
authors.initials: H
authors.lastname: Masu
authors.forename: Isao
authors.initials: I
authors.lastname: Azumaya
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Keiki
authors.initials: K
authors.lastname: Kishikawa
mesh_terms: D018360:Crystallography, X-Ray; D003500:Cyclization; D008958:Models, Molecular; D015394:Molecular Structure; D010616:Phenanthrenes / Q000138:chemical synthesis* / Q000737:chemistry; D010777:Photochemistry; D013237:Stereoisomerism; D013696:Temperature; D013997:Time Factors
chemical_list: D010616:Phenanthrenes; C031181:phenanthrene