pHarmacist (Hive Bee)
10-25-02 22:21
No 372654
      New Route to MDA  Bookmark   

Cyrax: here is one more 'great' synthesis, maybe you can check it up in Vogel or elswhere to confirm its validity, i'm not being cynical...




Note: in speed diagram, you can oxidize aldehyde directly to acid with some mild oxidizing agent such as Ag2O, instead of going tru NaBH4 --> alcohol ---> acid, we have to do that in MDA case since pi-bonds need to get reduced as well.

Never underestimate the power of retrosynthesis.
 
 
 
 
    Ment2bee
(Newbee)
10-25-02 23:32
No 372667
      New?  Bookmark   

I've seem something similar to this before.

../rhodium/chemistry /mda.dalcason.html

And they tell me to UTFSE.

For that same great taste that'll always wire you up and never let you down, make it a dexedrine.
 
 
 
 
    Rhodium
(Chief Bee)
10-26-02 01:38
No 372701
      Vogel and Advice  Bookmark   

Pharmacist: Everybody has enough money to be able to read Vogel's. It is archived at ../rhodium/chemistry /vogel3.html

Could you in the future please not post any total syntheses of psychoactive drugs without having any actual references for the reactions involved - especially not in this forum. Anyone here who has attended a basic college course in organic chemistry can draw a dozen of "possible reactions" leading to interesting compounds, but such schemes are of little use, as no directions at all are given about how to perform the reaction, do the workup, or purify the products - no hints of expected yields are mentioned either, something that is of utmost importance to gauge if a reaction is worthwhile or not.

 
 
 
 
    Cyrax
(Hive Bee)
10-26-02 15:20
No 372853
      This time, I have no remarks from synthetic point ...  Bookmark   

This time, I have no remarks from synthetic point of view.  OK, mabey one: K2Cr2O7 is some nasty shit.  Hexavalent chromium is highly carcinogenic, so using this reagent in the oxidation of [3] is not advisable.  But for the rest, everything looks just fine.
 
 
 
 
    Tricky
(Stunning)
10-26-02 17:37
No 372878
      More easy!  Bookmark   

pHarmacist, 2-phenylpropionic acid may be produced more easy:

Check out: http://www.orgsyn.org/orgsyn/prep.asp?rxntypeid=20&prep=V76P0169
Good Luck.

Wanna make laugh the GOD? - Tell him about your plans.
 
 
 
 
    Cyrax
(Hive Bee)
10-26-02 18:37
No 372883
      Tricky, I think your proposed synthesis will not ...  Bookmark   

Tricky, I think your proposed synthesis will not work.  In order to make a compound like [4] (in the synthesis of pHarmacist), we need to prepare a 2-benzylpropionic acid instead of a 2-phenylpropionic acid.

There is a significant difference in the reactivity of Ar-CH2CN and Ar-CH2CH2CN

If you look at the proposed reaction mechanism, you see that the base (K2CO3) abstracts a proton from the benzylcyanide, and the resulting carbanion reacts with the dimethylcarbonate.  The carbanion is stabilized by 2 electron sucking groups, hence it can easily be generated by a weak base.

With Ar-CH2CH2CN, it's a whole different story. 
First, you will need a far stonger base to generate the carbanion since the carbanion is only stabilized by one electon sucking group (K2CO3 will not work). 
And second, the place of proton abstraction is ambivalent.  Which proton will be abstracted?  The one from the methylene next to the aryl group, or the one from the methylene next to the cyano group.  I think both reactions will take place, especially if the base is strong enough.  You would need information about pKa of the protons on the methylene groups of Ar-CH2CH2CN, in order to devise a selective reaction (chose the right base).
Third, it is likely that the required stong base will react with the dimethyl carbonate.
 
 
 
 
    Tricky
(Stunning)
10-26-02 18:38
No 372884
      Sorry...  Bookmark   

about above topic...
it's my great mistake...frown
I've just confused 2-benzylpropionic acid with 2-phenylpropionic... fuck... it's visual fiction...
one more sorry

Wanna make laugh the GOD? - Tell him about your plans.