Reversal of regioselectivity (straight vs. cross ring closure) in the intramolecular [2+2] photocycloaddition of phenanthrene derivatives.
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.
Kohmoto
Shigeo
S
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
Hisamatsu
Shugo
S
Mitsuhashi
Hakuei
H
Takahashi
Masahiro
M
Masu
Hyuma
H
Azumaya
Isao
I
Yamaguchi
Kentaro
K
Kishikawa
Keiki
K
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
D010616:Phenanthrenes; C031181:phenanthrene