Piperonal is an MDXX precursor, not piperidine. Completely different chemicals.
Piperonal can be made into MD-P2P, the precursor for MDMA. However, it is much more easily made into MDA via an entirely different route. It is the route Shulgin used to make many of the substances in PIHKAL, from the various ring substituted benzaldehydes. Possession of piperonal will certainly land you in some bother.
Piperazines are becoming increasingly common in pills these days. A person I know who has seen countless lab results of pills over the last 8 or so years never saw piperazines until the past 12-18 months. Now lab results are routinely showing up as piperazines. They are still in the vast minority, but it is a lot more than the zero the person saw over the years before that.