Jones Oxidation (http://themerckindex.chemfinder.com/TheMerckIndex/NameReactions/ONR207.htm)
(http://themerckindex.chemfinder.com/TheMerckIndex/NameReactions/ONR207.htm) didn't give you a lot of piperonylic acid rather than piperonal. This is the case according to the Merck Index link. There is a niceSwern (http://themerckindex.chemfinder.com/TheMerckIndex/NameReactions/ONR390.htm)
(http://themerckindex.chemfinder.com/TheMerckIndex/NameReactions/ONR390.htm) type oxidation on Rhodium's page:DMSO Oxidation of Benzyl Alcohols to Benzaldehydes (https://www.thevespiary.org/rhodium/Rhodium/chemistry/benzaldehydes.dmso.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/benzaldehydes.dmso.html) which gives great yields and uses readily available reagents. There may be a possiblity of ether cleavage with HBr in polar aprotic solvents at 100oC but this is by no means a certainty. Methoxies certainly survive intact.Post 333551 (https://www.thevespiary.org/talk/index.php?topic=11449.msg33355100#msg33355100)
(Barium: "benzaldehydes to phenylacetones", Novel Discourse).