Here's a list of patents I found using the keyword "methylenedioxy":
6252092 safrole, 3,4-methylenedioxyphenyl compounds, etc.
5475024 benzodioxole derivatives
5153182 methylenedioxybenzene + paraformaldehyde + 37% HCl --> 3,4-methylenedioxybenzylchloride
5095128 piperonal
4731482 P2P's, LiI rearrangement of epoxides
4335263 dimethoxybenzaldehyde and dimethoxybenzylchloride
4157333 piperonal
http://www.geocities.com/dritte123/PSPF.html