Phenyl electron-transfer photooxidation

The photo-oxidation of the aryl-substituted cycloheptatrienes 7-(/ -methoxy-phenyl)cycloheptatriene and 7-, 1- and 3-(/ -dimethylaminophenyl)cycloheptatrienes to the corresponding radical cations in de-aerated acetonitrile solution was accomplished by electron transfer to the electronically excited acceptors 9,10-dicyanoanthracene, iV-methylquinolinium perchlorate, iV-methylacridinium perchlorate and l,T-dimethyl-4,4-bipyridinium dichloride. In the case of l- p-methoxyphenyl)cycloheptatriene (62), deprotonation of the radical cation occurs successfully, compared with back electron transfer, to give a cycloheptatrienyl radical (63) which undergoes a self-reaction forming a bitropyl. If the photooxidation is done in air-saturated acetonitrile solution containing HBF4 and one of the acceptors, the tropylium cation is formed. Back electron transfer dominates in the / -dimethylaminocycloheptatrienes and the formation of the cycloheptatrienyl radical is prevented. 

DL-a-acetamido-P-hydroxy-p-nitropropiophenone has been prepared from L-(+)-threo-(p-nitrophenyl)-2-aminopropan-l,3-diol and acetic anhydride followed by photooxidation in the presence of acidic KBrOs and HBr. Photosensitized electron transfer reactions of tri-1-naphthyl phosphate and di-1-naphthyl methyl phosphate using 9,10-dicyanoanthracene are reported to lead to the formation of 1,1 -binaphthyl, but no reaction occurs for mono-1-naphthyl and di- or tri-phenyl esters. Irradiation of bis(3,4-methylenedioxyphenyl) methylphosphonate in the presence of DCA induces single electron oxidation followed by intramolecular rearrangement and gives 2-(3,4-methylenedioxyphenyl)-3,4-methylenedioxy-phenyl methylphosponate. ... 

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