I am having trouble finding any sort of reference for piperic acid to piperonyl.
It would be nice to have a more selective oxidation from piperic acid.
I can't find this
Fittig and Mielch, Ann., 152 (1869) 25)
Could some one else get these:
J. Am. Chem. Soc. 94, 4024 (1972);
J. Org. Chem. 43, 1532 (1978)
How about these other routes to the aldehyde:
chromyl trichloroacetate: Liebigs Ann. Chem. 659, 20 (1962)
t-butyl iodoxybenzene: Tetr. Lett. 26, 4955 (1985)
KMnO4 in THF-H2O: J. Org. Chem. 51, 3213 (1986)
NaIO4-OsO4: J. Org. Chem. 21, 478 (1956)
Synthesis 1984, p 431-3
J. Chem Research - Synopses 1986, p 458-9
Dimethyl polyethylene glycol - see J. Org. Chem. 43, p 1532, (1978).