Photochemical Electron-Transfer Generation of Arylthiirane Radical Cations with Tetranitromethane and Chloranil - Some Novel Observations

MARCELO PUIATTI; JUAN E. ARGÜELLO; ALICIA B. PEÑÉÑORY

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY

WILEY-VCH Verlag GmbH & Co. KGaA,

Lugar: Weinheim, Alemania; Año: 2006 vol. 2006 p. 4528 - 4528

1434-193X

he radical cations from 2,2,3,3-tetraphenylthiirane (1a), 2,2-bis(4-methoxyphenyl)-3,3-diphenylthiirane (1b), and trans-2,3-diphenylthiirane (1c) have been generated by photoinduced electron transfer (PET) reactions with tetranitromethane [C(NO2)4] and chloranil (CA). A charge-transfer complexe (CTC) absorption is observed by UV/Vis spectroscopy between thiiranes (1) and C(NO2)4. On the other hand, quenching studies with azulene suggest that the ET reaction occurs between thiiranes and the triplet CA (3CA). The photochemical reaction of the CTC between thiiranes 1 and C(NO2)4 yields mainly the corresponding alkenes from the fragmentation of the radical-cation intermediate 1b·+, together with the products derived from nitration on the phenyl rings. However, oxygen transfer to afford the sulfoxides is not found. A marked solvent effect is observed in this reaction, with cage coupling favored in CH2Cl2 (nitration derivatives as primary products) and non-cage coupling observed in CH3C