It seems that dried plant material is not likely to contain more than 3.5 grams chlorogenic acid per kg.
http://www.startechhealth.com/phenol.html (http://www.startechhealth.com/phenol.html)
Chlorogenic acid is 50% caffeic acid and say that you get a 90% yield on the conversion, so you get about 1.6 grams of caffeic acid per kg of dried plant material. Now you need 3 more chemical steps, say each step gives a 90% molar yield, also the mole weight of safrole is 90% that of caffeic acid so 1.6 gram X (.9)4 = 1.0 gram of isosafrole. So to get 100 grams of isosafrole you are looking at starting with the extraction of 100 kg of dried apples.
I think demethylation of the readily available eugenol via alkali fusion is a much better potential route to isosafrole for those people who can't obtain safrole containing essential oils.
Agreed - waste plant matter will not do but coffee has much more chlorogenic acid. "13 g roasted coffee per person per day contains about 765 mg of chlorogenic acid" which is nearly 6%, from which you can get about 2.5% caffeic acid.
http://ist-socrates.berkeley.edu/mutagen/ames.PNASII.html (http://ist-socrates.berkeley.edu/mutagen/ames.PNASII.html)
Post 314066 (https://www.thevespiary.org/talk/index.php?topic=9114.msg31406600#msg31406600)
(terbium: "Eugenol demethylation via alkali fusion.", Methods Discourse)