Obtention of two anomers of imidazolone during the type I photosensitized oxidation of 2′-deoxyguanosine

Abstract

The β-furanose anomer of imidazolone (β-dIz) is the main product of the photosensitized oxidation of the natural 2′-deoxyguanosine in the presence of benzophenone, a type I photosensitizer, but the α-furanose anomer (α-dIz) is also formed through an imine intermediate during the photochemical reaction. This anomerization phenomenon has been confirmed by using the α-anomer of 2′-deoxyguanosine. In addition, the chemical oxidation of α- or β-dG by Mn-TMPyP–KHSO₅ provides the α- or β-furanose anomers, respectively, in an almost quantitative yield, and thus represents a method of choice for the synthesis of both dIz stereoisomers.