5-Allylvanillin was isomerized by low temperature caustic fusion io yield 5-propenylvanillin. Ethyl vanillate and ethyl orthovanillate were converted to ethyl 5-allylvanillate and ethyl 5- allylorthovanillate, respectively, and these were treated directly with fused caustic to yield 5- propenylvanillic acid and 5-propenylorthovanillic acid. Oxidation of the propenyl compounds with nitrobenzene and alkali at 160-165" gave the corresponding formyl derivatives as the ...
[Hoelz, Lucas Villas-Boas; Goncalves, Biank Tomaz; Barros, Jose Celestino; Silva, Joaquim Fernando Mendes Da Molecules, 2010 , vol. 15, # 1 p. 94 - 99]