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All posts   Subject: 4-Me 4-hydroxy trans crotonic acid, OTC?   Please login to post  

 
    yei
(Newbee)
10-11-04 00:16
No 535251
      4-Me 4-hydroxy trans crotonic acid, OTC?     

4-alkyl 4-hydroxy trans-crotonic acids & their salts are potent GHB receptor ligands. How about an OTC synthesis from levulinic acid?

The problem is slightly tricky, because just heating levulinic acid will produce a lactone with the wrong stereochemistry, even if hydrolyzed.
Molecule: Good, Bad ("CC(O)/C=C/C(=O)O.CC(O)/C=C\C(=O)O")



So here is my idea:


Molecule: ketalize ("CC(=O)CCC(=O)O.C(OCC)(OCC)OCC>>CC(OCC)(OCC)CCC(=O)OCC")

1. convert levulinic acid into its ketal with acid/triethyl or trimethyl orthoformate. Yield 90%

Molecule: pyrolize ("CC(OCC)(OCC)CCC(=O)OCC>>CC(OCC)/C=C/C(=O)OCC.OCC")

2. Pyrolyze the ketal in the presence of acidic catalyst to produce an enol ether, which will isomerize (I think) at the temperature employed (~250 C)to conjugate with the carbonyl group. Yield probably about 90% (so says organicum)

Molecule: hydrolyze ("CC(OCC)/C=C/C(=O)OCC>>CC(O)/C=C/C(=O)O")

3. Hydrolyze the ether and ester under acidic conditions to yield the desired compound. Consume and enjoy. Yield ??

At worst, I suppose this method would produce a racemic mixture, but in actuality, the steric hinderance would probably make the trans-isomer the predominant one. Hopefully.


Ketalization of levulinic acid:
JACS 1955, 4069
Leibig's Annalen 1983, 913
Carbohydrate Research #319,63

I will link the last article shortly.

Would this work?

It's good to bee back! Don't trust your computer!!
 
 

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