THE PHOTOCHEMICAL BEHAVIOR OF SOME o-NITROSTILBENES

Photocyclization Reactions of Aryl Polyenes. IV. The Syntheses of Isatogens and Isatogen-like Compounds

“…The irradiation of 1-o-nitrostilbene gave 2-phenylisatogen (5), a reaction which can be more readily explained in the photochemistry of the nitro group (5,6) than in the photocyclization-oxidation of the diary1 polyene.…”

“…The photochemical reaction of o,o1-dinitrostilbene gave 2-(0-nitropheny1)isatogen (5). The analogous photo-reactions of 1,4-di-o-nitrophenyl-l,3-butadiene (5c) and 1,6-di-o-nitrophenyl-1,3,5-hexatriene (5d) were attempted to determine the affect of the additional nitro group Can.…”

“…The mechanism of formation of isatogens from the photoreaction of o-nitrostilbenes has been discussed by other workers (5,6) evidence regarding postulated intermediates is lacking. The formation of 11 and 14 by photochemical and thermal means respectively is significant in the fact that the steric requirements necessary for the formation of isatogens (fivemembered ring) is not stringent and the formation of six and seven-membered ring isatogenlike compounds is readily achieved.…”

Synthetic Aspects of Photochemical Electron Transfer Reactions

“…A number of electronaccepting sensitizers, including quinones, (147) nitrogen heterocycles, dyes, (362) and polycyclic aromatic hydrocarbons, (63) have been employed as decarboxylation catalysts. The mechanism for these reactions appears to involve photochemically activated electron transfer to generate the arylacetic acid radical cations 482 which then readily lose carbon dioxide to form the corresponding benzyl radicals, a process analogous to the deprotonation route of arylalkyl cation radicals described earlier in this chapter (Section 1.2.5.2).…”

Photochemical studies on 9-nitroanthracene

“…Irradiation of o_-nitrostilbenes were also reported to give this class of compound (47). An example is the trans formation of LXII to LXIII.…”