Rhodium (Chief Bee)
08-10-02 02:10
No 343683
      Hydrocinnamic acid to P2P - byzantine or real?  Bookmark   

3-Phenylpropionic acid (Hydrocinnamic acid) can be made in many ways (or bought for about $100/kg), and by subjecting it to Hell-Vollhardt-Zelinski reaction conditions (PBr3/Br2) you'll afford 2-Bromo-3-Phenylpropionic acid, which in turn can be reduced to 2-bromo-3-Phenyl-1-propanol (allylbenzene bromohydrin) using for example NaBH4 together with I2 or H2SO4.

By refluxing this bromohydrin lightly in dilute NaOH it will cyclize through an intramolecular Williamson etherification to form 2-benzyloxirane (allylbenzene epoxide), which finally is refluxed with LiI in EtOAc for a few hours to effect the isomerization of the epoxide to its methyl ketone; Phenyl-2-Propanone.

(Hive Bee)
08-10-02 08:31
No 343945
      yield  Bookmark   

Any thoughts on the yield of P2P when using hydrocinnamic acid?

Doped(TM) since 19.... euhm... a long time smile
(Hive Bee)
08-15-02 02:40
No 345489
      Energetically unfavorable.  Bookmark   

R-CO2H's dislike being reduced, although I've never tried DIBAL.
All in all, I would predict a somewhat low yield overall. 
Even with good yields in each step, there would still be a few too many steps there (5) to be of much utility.

 . . .

Rapture Tastes So Sweet.