No direct synthesis of safrole has been recorded, the most recent attempt being that of Baker and Robinson (JCS, 1925, 127, 1424), who distilled the product of the action of silver oxide and water upon gamma-piperonylpropyltrimethylammonium iodide, but obtained isosafrole, the double bond moving into the position of greater stability.
I thought the first safrole synthesis was attributed to the French scientist Moureu. He used the Perkin reaction and published a paper (in French) in the late 1890s. I have the article but can't find it right away.
J. Chem. Soc. 2925-2932 (1926) (https://www.thevespiary.org/rhodium/Rhodium/pdf/ortho-piperonal.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/ortho-piperonal.pdf)
Safrole (III)
1,2-Dihydroxy-4-allylbenzene (10 g) and methylene iodide (18 g) were dissolved in pure dry acetone (35ml) and finely powdered, freshly ignited potassium. carbonate (20g) was gradually added with shaking to prevent caking. After gently refluxing on the water-bath for 12 hours, the acetone was removed, the product was made acid with dilute sulphuric acid and extracted with ether, and the ethereal solution was repeatedly washed with dilute aqueous sodium hydroxide and finally with water, dried over sodium sulphate, and evaporated. On carefully distilling the residue under reduced pressure, methylene iodide first passed over; when this had been completely removed, a fraction, bp 100-101.5°C/10-11mmHg, consisting of 2.5 g. of a clear, colourless oil, was collected. This was identified as safrole by its characteristic odour and by preparing its pentabromo-derivative by gradually adding excess of bromine below 0°C and allowing the mixture to stand for some hours; the solid substance which had separated, after recrystallising from ethyl alcohol, melted at 169°C, and a mixed melting point with the derivative prepared from ordinary safrole showed no depression. The oil had nD20 1.5381. As an additional proof of identity, 1.35 g of the synthetic substance were nitrated under the conditions laid down by Foulds and Robinson (JCS, 1914, 105, 1963), the nitro-derivative was reduced with tin and hydrochloric acid, and the crude 6-aminosafrole acetylated; the acetyl derivative crystallised from methyl alcohol in colourless needles, mp 162-163°C, and a mixed melting-point determination with the corresponding derivative from naturally occurring safrole showed no depression.
Do you guys think that increasing this reaction by tenfold (mole-wise) has any major problems?