Computational studies of electronic circular dichroism spectra predict absolute configuration assignments for the guanine oxidation product 5-carboxamido-5-formamido-2-iminohydantoin.

Oxidation of the guanine heterocycle by two electrons can yield the chiral product 5-carboxamido-5-formamido-2-iminohydantoin (2Ih). The 2Ih free base enantiomers were synthesized from 2'-deoxyguanosine oxidized with a Cu(II)/H2O2 oxidant system followed by hydrolysis of the N-glycosidic bond. These isomers were each studied by electronic circular dichroism spectroscopy for determination of their absolute configurations. Time-dependent density functional theory calculations of the expected spectra were completed in both the gas phase and with solvent modeling in order to interpret the experimental spectra and provide the absolute configuration assignments.