The first step: take 14.80 g of 4-allyl anisole into a 250 ml flask, slowly add an appropriate amount of pyridine perbromide as a brominating agent, add an appropriate amount of Zn as a catalyst, and react for 3 h. The fraction at 152°C was distilled off under reduced pressure, which was 2-bromo-4-allyl anisole.
The second step: take 18.70 g of 4-bromo-anisole, add ethyl magnesium chloride, 2,5-dimethylphenyl magnesium bromide, react at 40 ° C for 2 h, and then slowly add 12.10 g of allyl bromide, After the reaction for 5h, the fraction at 150°C was distilled off under reduced pressure, which was 4-bromo-2-allyl anisole.
The third step: Dissolve 2.38 g of nickel hexahydrate in 2 ml of water, add 5.25 g of triphenylphosphine, dissolve in 75 ml of glacial acetic acid, and react at room temperature for 24 h. Olive green microcrystals are precipitated in the reaction solution. Filter, wash with glacial acetic acid, and dry in a desiccator with sulfuric acid or potassium hydroxide in a vacuum to obtain dark blue crystals.
The fourth step: take 150 ml of anhydrous ether into a 250 ml flask, add 3.00 g of magnesium strips, soak for 1 h, and then slowly add the prepared 4-bromo-2-allyl anisole, reaction 3 h, make 4-bromo-2-allyl anisole into Grignard reagent, then add the prepared 2-bromo-4-allyl anisole into it, react for 12 h, distill out under reduced pressure Fractions below 150°C are obtained to obtain Pure Honokiol methyl ether, which is then hydrolyzed, finally extracted with ethyl acetate and water, concentrated to dryness under reduced pressure, and purified by silica gel column chromatography (ether:hexane=1:2) to obtain white crystals The product is Pure Honokiol.