Synthesis of 4-Hydroxy-3-Ethoxy-1-Allyl-Benzene From 4-Hydroxy-3 -Methoxy-1 -Allylbenzene (Eugenol)

Influence of the chemical structure on the odor qualities and odor thresholds of guaiacol-derived odorants, Part 1: Alkylated, alkenylated and methoxylated derivatives

“…5-Allylguaiacol (chavibetol, 5-allyl-2-methoxyphenol, entry 22, Fig. 1e) (Hirao, 1936) An ethereal solution of methylmagnesium iodide (3.4 mL, 3 M) was poured into a solution of eugenol methyl ether (4-allyl-1,2-dimethoxybenzene) (2 g, 11.22 mmol) in 5 mL dry xylene. After 2 h at 160-180°C under reflux, HCl (10 mL, 1 N) was added.…”

Synthesis of isomers of eugenol

“…3-Allyl-2-methoxyphenol (III) was refluxed with alcoholic KOH for 16 hr by a method analogous to the preparation of isochavibetol [2]; bp 109 °C/7mm, nnormalD25=1.556. As indicated by the infrared spectrum the product was an impure mixture of cis and trans 2-methoxy-3-propenylphenol.…”

“…The chavibetol was characterized by conversion to isochavibetol (mp 95 to 96 °C) as described by Hirao [2].…”

“…Three procedures were considered for the synthesis of 3-allyl-2-methoxyphenol (III). (1) Partial demethylation of l-allyl-2,3-dimethoxybenzene (a preparation analogous to that described by Hirao [2] and Schöpf and coworkers [3] for the synthesis of Chavibetol). The isomeric products II and III appeared to be difficult to separate by techniques other than gas chromatography.…”

“…The preparation of IV was also attempted by several methods. The synthesis of pure chavibetol described by Hirao [2] and Schöpf and coworkers [3] proved to be laborious in the separation of chavibeto from its eugenol isomer. This separation has now been greatly facilitated by the use of gas chromatography.…”