The base compound of the MDxx class is 3,4-methylenedioxyphenethylamine (MDPEA), and the prototypical agent of this class is 3,4-methylenedioxy-N-methylamphetamine (MDMA; "ecstasy").
The basic compound for the MDxx group is 3,4-methylenedioxyphenethylamine (MDPEA), with MDMA serving as an exemplary member of this class.