(Chief Bee)
10-03-03 16:59
No 462464
(Rated as: excellent)
This is an excellent article, with a very good review of other methods which has been used for the rearrangement of epoxides to carbonyl compounds, and for our interests the rearrangement of propenylbenzene epoxides to phenylacetones is the most interesting transformation (such as isosafrole expoxide to MDP2P).
The reviewed methods include Pd(OAc)2/PPh3, BF3ˇEt2O, MgBr2, lithium salts, Indium chloride, Bismuth salts like BiOClO4/Bi(OTf)3, methylaluminium bis(4-bromo-2,6-di-tert-butylphenoxide) (MABR) as well as their own invention, to use catalytic (1 mol%) IrCl3ˇxH2O, which gives 100% conversion of propenylbenzene epoxide to P2P (THF/50°C/2h).
Iridium-Catalyzed Meinwald Epoxide Rearrangement
Iyad Karamé, M. Lorraine Tommasino and Marc Lemaire
Tet. Lett. 44(41), 7687-7689 (2003) (../rhodium /meinwa
Abstract
A novel and easy to handle procedure for the regioselective rearrangement of epoxides has been developed, based on an iridium catalyst.
(Chief Bee)
01-09-04 16:30
No 481505
(Rated as: good read)
Reaction of Phenyl-1,2-Epoxypropane with Fluorosulfuric Acid
J. Org. Chem. 46, 2920-2923 (1981)
To 6 mL of FSO3H cooled in an ice-bath was added 2.5 g of propenylbenzene epoxide dropwise in 50 min. The black reaction mixture was carefully added to ice in the presence of 200 mL of CHCl3. After extraction of the aqueous phase, it was saturated with NaCl and extracted with 200 mL of CHCl3. The combined organic extracts were washed with saturated NaCl solution (3x200 mL), dried over MgSO4, filtered, and concentrated under vacuum to yield 2.2 g (88%) of phenyl-2-propanone as an oil.
The Hive - Clandestine Chemists Without Borders
(Chief Bee)
06-21-04 15:39
No 514676
(Rated as: good read)
Lewis acid-promoted selective rearrangement of trisubstituted epoxides to aldehydes or ketones
Keiji Maruoka, Noriaki Murase, Ronan Bureau, Takashi Ooi and Hisashi Yamamoto
Tetrahedron 50(12), 3663-3672 (1994) (../rhodium/pdf /epoxide2keto
Abstract
Rearrangement of trisubstituted epoxides has been effected under the influence of various Lewis acids. Among these, methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) (MABR) can be selectively rearranged from trisubstituted epoxides to aldehydes, while antimony pentafluoride is employable for selective rearrangement to ketones under mild conditions.
The Hive - Clandestine Chemists Without Borders