Intramolecular 10,10a-[2+2] photocycloaddition reactions of phenanthrenes with linked styrene

Synthesis of 3‐Oxatricyclo[7.2.0.01,5]undeca‐7,10‐dienes through Intramolecular Photocycloaddition Reactions of Alkenes to 1,8 a‐Position of Naphthalene Ring

“…A 1.0×10 −4 M cyclohexane solution of trans ‐ 6 aa in an optical quartz cell was irradiated with UV light, and change in the absorption spectrum was monitored (Figure 2). In a similar reaction of a phenanthrene derivative in an earlier study, the UV absorption spectrum became similar to that of the initial photocycloadduct at the 9,10‐position (corresponding to the 1,2‐position of naphthalene) with isosbestic points [86] . However, when the naphthalene derivative trans ‐ 6 aa was subjected to the same measurement, the isosbestic point did not appear, and only the absorbance decreased.…”

“…We have previously investigated the intramolecular photoreaction of compounds connecting a phenanthrene and a styrene, and found that unusual photocycloadducts are formed at the 10,10a‐position of phenanthrene (corresponding to the 1,8a‐position of naphthalene) along with usual photocycloadducts at 9,10‐position of phenanthrene (corresponding to the 1,2‐position of naphthalene) [86] . Based on that knowledge, if one of the three benzene rings of phenanthrene is removed from the terminal near the cyano group, that is, 1‐(5‐aryl‐2‐oxapent‐4‐enyl)‐2‐cyanonaphthalene 6 is prepared, it might be possible to design a system in which the photocycloaddition reaction at the 1,8a‐position of the naphthalene ring proceeds efficiently.…”

Photoinduced Electron Transfer-Promoted Reactions Using Exciplex-Type Organic Photoredox Catalyst Directly Linking Donor and Acceptor Arenes

“…In the case of 6, the radical generated via decarboxylation dimerizes to give 11 and BET from the generated radical anion of 1 does not occur, indicating that 1 does not work as a catalyst in this photodecarboxylation. In general, the intramolecular exciplex is considered an important intermediate to cycloaddition [25,26]. However, in this case, the intramolecular exciplex of 1 can work as a redox catalyst for substrates containing alkene or aromatic ring functional groups.…”