I just read on Wikipedia that piperonal reacted with nitoethane makes MDP2NP.

"Many other drugs of the amphetamine class are produced in a similar fashion, where substituted benzaldehyde derivatives are used to produce a different nitrostyrene, which is later reduced to the desired amine. One such reaction is the Knoevenagel condensation of piperonal with nitroethane, yielding 3,4-methylenedioxy-1-phenyl-2-nitropropene, or MDP2NP. This is reduced to 3,4-methylenedioxyamphetamine (MDA) which can be methylated to 3,4-methylenedioxymethamphetamine (MDMA)."[9]

Also note that MDP2NP is not very stable and must be kept in a refrigerator or used right away.