Photoinduced electron transfer cleavage of oxetane adducts of uracil and cytosine

Abstract

Oxetane adducts of 1,3-dimethyluracil and 1,N⁴,N⁴-trimethylcytosine were prepared and their behavior under photoinduced electron transfer was examined by fluorescence quenching, laser flash photolysis and product analysis. The excited state electron donor, N,N,N′,N′-tetramethylbenzidine, was shown to photosensitize a net cycloreversion of these oxetanes to give the pyrimidine derivative and benzophenone. It is demonstrated that this reaction occurs via the anion radical of the oxetane and that the latter cleaves very rapidly (>10⁷ s⁻¹).