American Chemical Society
ja025697y_si_001.pdf (3.43 MB)

Stepwise Cycloreversion of Oxetane Radical Cations with Initial C−O Bond Cleavage

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journal contribution
posted on 2002-05-15, 00:00 authored by Miguel A. Miranda, M. Angeles Izquierdo
2,4,6-Triaryl(thia)pyrylium salts have been used as electron-transfer photosensitizers for the cycloreversion of the oxetane ring system. The radical cation of 2,3-diphenyl-4-hydroxymethyloxetane (1) undergoes stepwise splitting via initial O−C2 cleavage. Spin and charge in the resulting intermediate are located in the oxygen and carbon atoms, respectively. Subsequent intramolecular nucleophilic attack produces 2,3-diphenyl-4-hydroxytetrahydrofuran (4a). Formation of this product occurs in the submicrosecond time scale, competing with C3−C4 cleavage to the detectable (λmax = 470 nm) trans-stilbene radical cation.