- Method for Industrial Production of Optically Active Fluoroalkyl Ethylene Oxide
-
It is possible to produce an optically active fluoroalkyl chloromethyl alcohol with a high optical purity and a good yield by treating a fluoroalkyl chloromethyl ketone with a microorganism having an activity for asymmetrically reducing the ketone or an enzyme having the activity. Then, it is possible to obtain a fluoroalkyl ethylene oxide by treating the alcohol with a base. Industrial implementation of the production method of the present invention is easy.
- -
-
Paragraph 0139; 0140
(2018/11/21)
-
- ISOSELECTIVE POLYMERIZATION OF EPOXIDES
-
The present invention provides novel bimetallic complexes and methods of using the same in the isoselective polymerization of epoxides. The invention also provides methods of kinetic resolution of epoxides. The invention further provides polyethers with high enantiomeric excess that are useful in applications ranging from consumer goods to materials.
- -
-
Page/Page column 69; 77-78
(2009/04/25)
-
- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
-
The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
-
p. 1307 - 1315
(2007/10/03)
-
- Chiral Synthesis via Organoboranes. 40. Selective Reductions. 55. A Simple One-Pot Synthesis of the Enantiomers of (Trifluoromethyl)oxirane. A General Synthesis in High Optical Purities of α-Trifluoromethyl Secondary Alcohols via the Ring-Cleavage Reactions of the Epoxide
-
An extremely efficient one-pot asymmetric synthesis of either enantiomer of (trifluoromethyl)oxirane (3,3,3-trifluoro-1,2-epoxypropane, 4) in 64percent yield and 96percent ee has been achieved via the asymmetric reduction of the commercially available 1-bromo-3,3,3-trifluoro-2-propanone with either (+)- or (-)-B-chlorodiisopinocampheylborane (Aldrich: DIP-Chloride), followed by ring closure of the intermediate chloroborinate, IpcBCl.The ring cleavage reactions of 4 provide a general synthesis of chiral trifluoromethyl carbinols without loss of optical activity.Thus we have synthesized 1-amino-3,3,3-trifluoro-2-propanol, 1-azido-3,3,3-trifluoro-2-propanol, 1-(diethylamino)-3,3,3-trifluoro-2-propanol, 1-cyano-3,3,3-trifluoro-2-propanol, 1,1,1-trifluoro-2-propanol, 1,1,1-trifluoro-2-octanol, 1-phenyl-3,3,3-trifluoro-2-propanol, 1-ethoxy-3,3,3-trifluoro-2-propanol, and 1,2-dihydroxy-3,3,3-trifluoropropane, in 61-88percent yields and in 96percent ee by the cleavage of 4 with the appropriate nucleophile.
- Ramachandran, P. Veeraraghavan,Gong, Baoqing,Brown, Herbert C.
-
-
