Look what I found while buying the stuff for my eugenol experiments...
I used TFSE for kaffeesaure, Kaffeesäure and coffee combined with acid, and didn't find anything that looks like this, so I thought I should mention it.
This is 'kaffeesäure' or 'coffee acid':
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000511810-caffeesaure.gif)
I first read about it here:
http://www.fslemi.uni-bonn.de/gewuerze/html/stralsklasse/sel.html (http://www.fslemi.uni-bonn.de/gewuerze/html/stralsklasse/sel.html)
References are here http://www.paracelsus.de/heilv/natur_177.html (http://www.paracelsus.de/heilv/natur_177.html)
and here http://www.g-netz.de/Health_Center/heilpflanzen/zzwirkstoffe/phenolsaeuren.shtml#phenolsaeuren (http://www.g-netz.de/Health_Center/heilpflanzen/zzwirkstoffe/phenolsaeuren.shtml#phenolsaeuren)
.
The latter also has a list of sources (other than the obvious considering the name).
Other names appear to be 3,4-Dihydroxyzimtsäure (= 3,4-dihydroxycinnamaldehyde) and 3-O-Caffeoyl-D-chinasäure, but I haven't found it in the 84th edition of the CRC.
Searching on the web it appears to be freely availabe in pure form(5 g = 19 euros at the first site I found it). Take note: you have to type the a-umlaut (ä) correctly in order to find anything in Google.
Am I on to something here, or am I just really showing my newbee status in an almost obscene way? :P
The real question is: is it economically and practically feasible to change the carboxyl group to a methyl group (either before or after methylenation of the hydroxyl groups on the road to safrole, as described here (https://www.thevespiary.org/rhodium/Rhodium/chemistry/methylenation.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/methylenation.html).
The moving of the double bond can of course be found here (https://www.thevespiary.org/rhodium/Rhodium/chemistry/isomerizafrole.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/isomerizafrole.html).
I don't have the knowledge to answer this question yet, hope you can help.
do a search:
Post 122772 (https://www.thevespiary.org/talk/index.php?topic=12530.msg12277200#msg12277200)
(dormouse: "MDA from Coffee -Wizard X", Serious Chemistry)
Post 323392 (https://www.thevespiary.org/talk/index.php?topic=11299.msg32339200#msg32339200)
(mellow: "MDP2P from waste vegetation?", Novel Discourse)
Reducing carboxylic acids to alkanes is rather impractical. How about oxidising 3,4-dihydroxycinnamic acid to protocatechualdehyde with modified permanganate (as ning suggested), followed by methylenation? It may be best to first methylenate to 3,4-methylenedioxycinnamic acid, which would give piperonal directly upon oxidation. The following article deals with the oxidation of plain cinnamic acid to benzaldehyde with permanganate on alumina:
Heterogeneous Permanganate Oxidations. 5. The Preparation of Aldehydes by Oxidative Cleavage of Carbon-Carbon Double Bonds
Donald G. Lee,* Tao Chen, and Zhao Wang
J. Org. Chem. 1993, 58, 2918-2919
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Also see Cleavage of alkenes to aldehydes using potassium permanganate (https://www.thevespiary.org/rhodium/Rhodium/chemistry/alkene2aldehyde.kmno4-thf.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/alkene2aldehyde.kmno4-thf.html).