Activation and transfer of oxygen-X : A new autoxidative rearrangement of tetrahydropteridines

Abstract The structure 2a proposed by Viscontini and Okada for the autoxidation product of 5-methyl-6,7-diphenyl-5,6,7,8-tetrahydropterin 1 was found to be incorrect. Alternative structures 3a , 3b were deduced from spectroscopic data. X-ray analysis of the acetyl derivative 8 proved the oxidation product to be 2-amino-8-methyl-4,9-dioxo-cis-6,7-diphenyl-6,7,8,9-tetrahydro-4H-pyrazino(1,2-a)-s-triazine 3a . The mechanism of the rearrangement may involve an intermediate 4a-peroxy-pterin. A similar rearrangement on peroxide-level was observed for the corresponding lumazine 14 .