Natural Science Forum / Chemistry / Organic Synthesis / July 2006

Hi.

The following excerpt from a publication might help you... However, I
wonder if it is a good idea to use this method to epoxidate a molecule
containing an unprotected phenol moiety (if I understood clearly what
you are doing). I see no reason why it shouldn't work but in all the
exemples I saw the phenols were protected... but I searched only during
10 min using Beilstein Xfire and didn't look specifically for phenols,
so you can make your own search and tell us what you found.

J. Med. Chem. 1984, 27, 831-836:

General Epoxidation Procedure (Method A).
To 50 mmol of the appropriate olefin dissolved in 50 mL of CH2Cl2, a
solution of 55 mmol of m-chloroperbenzoic acid in 110 mL of CH2Cl2 was
added dropwise at 20-25 ?C under stirring. After 2 h an additional 4
mmol of m-chloroperbenzoic acid in 10 mL of CH2Cl2 was added to the
resulting suspension. After stirring for an additional 2 h, the
suspension was filtered, and the filtrates were washed successively
with aqueous solutions of Na2S03, NaHCO3, and water and then dried over
Na2S04, and the solvent was removed on the rotovapor. The resulting
products were almost pure on TLC (toluene) and showed NMR data in full
agreement with the structures (80-95% yields). These products were used
without further purification in the next steps.

Vogel's recommends filtering, washing with 10% NaHCO3, stripping, and
distilling the epoxide if possible.  (It's is a great reference for
practical procedures for common organic reactions--you should get yourself a
copy.)  If styrene oxide can be distilled in good yield at 191 - 192 C/760
torr (!), surely you can find conditions where you can vacuum distill your
epoxide--even if just by Kugelrohr.  I doubt it would survive on silica gel;
you might try Florisil.

Eric Lucas