Casually I have a refence for methylenation of methyl 3 methoxy 4,5 hydroxy benzoate, it's the previous text in CA to the isosafrol epoxide.
I don't know if it can be interesting, but may be:
CA 107:39789s
Methyl 3 methoxy 3,4 hydroxy benzoate (I) was cyclocondensed with CH2Cl2 in the presence of alakli metals halides, e.g. KI, NaI , to give the methylene dioxy benzaote derivate . This procedure shortened the reaction time from 40 to 2.5 h. and increased the yield of methyl 3 methoxy 3,4 methylenedioxy beonzoate from 68 to 79 %. A mixt. of K2CO3, CH2Cl2 and NaI in DMF was refluxed for ~ 0.5 hours; I in DMF was added over 15-30 min. , more CH2Cl2 was added , and the resulting mixt. refluxed for 1-2 hours to give II 79 %.