Autoxidation of the bis(O-demethyl)-p-hydroquinone metabolite of the psychotomimetic amine 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) at pH 7.4 leads exclusively to a bicyclic imino quinone. This imino quinone is a good alkylating agent, forming covalent adducts via 1,4 addition to thiols. The autoxidation appears to be dependent on trace metal catalysis and is dramatically inhibited...