Reaction of 4,7-dimethylbenzofurazan with singlet oxygen

4,7-Dimethylbenzofurazan (1) was transformed by 1O2 produced by irradiation of C60 into 4,7-dimethylbenzofurazan 4,7-endoperoxide (2) in CDCl3 or CD2Cl2 at 0°C in excellent yields. The endoperoxide decomposed back to 1 at room temperature. When tetramethylethylene (TME) was added to the decomposing endoperoxide at 37°C, the hydroperoxide from reaction of TME with 1O2 was detected. The rate constant for the reaction of 1O2 with 1 was determined by the quenching of 1O2 luminescence to be 4.8×103 M−1 s−1.