Structural correction of the 3-methylindole oxidatively-coupled dimer

The main product of the horseradish peroxidase-mediated oxidative coupling of 3-methylindole by H2O2 has been found to be the same compound previously obtained from chemical, radiolytic, and anodic oxidation of 3-methylindole and claimed to be a hexahydrofurodiindole of undefined stereochemistry (meso versus d,l). Single-crystal X-ray diffraction analysis of the compound, aimed at determining the stereochemistry, revealed that the actual product is an isomer, 7,8-dimethyl-2-oxa-4,11-diazadibenzo[e,i]tricyclo[5.4.0.03,8]undecane that derives from hydrolytic reorganization of the initially formed biindoline radical coupling product.