129443-08-9Relevant academic research and scientific papers
Syntheses of (R)- and (S)-enantiomeric 1,1,1-trifluoromethyl-2-alkanols with high enantiomeric purity controlled through derivatization with l-menthyl phthalate
Mikhailenko, Vadim,Yedamenko, Daria,Vlasenko, Ganna,Krivoshey, Alexander,Vashchenko, Valerii
, p. 5956 - 5959 (2015)
Readily available l-menthyl phthalate has been shown to be an effective derivatizing agent for determination of the enantiomeric purity of alkyl- and aryl-substituted 1,1,1-trifluoromethyl-2-alkanols using HPLC and GC. It has been shown that a previously described protocol for one-step enzymatic kinetic resolution results in the formation of the desired 1,1,1-trifluoromethyl-2-alkanols with 96-98% ee. Enrichment of the (R)-isomer of trifluoromethyl alkanols by repetition of the enzymatic hydrolysis procedure was found to increase the ee up to 99.9%. Furthermore, excessive conversion of the corresponding esters during enzymatic hydrolysis allowed enantiomerically pure (S)-1,1,1-trifluoromethyl-2-alkanols to be obtained.
Resolution of 1,1,1-trifluoro-2-octanol by Pseudomonas sp. lipase encapsulated in aggregated silica nanoparticles
Wu, Zhuofu,Li, Wenzhao,Wang, Zhi,Qin, Ling,Liu, Yunling,Huo, Qisheng,Li, Zhengqiang
, p. 6103 - 6109 (2014)
Lipase from pseudomonas sp. (PSL) was encapsulated in stacked silica nanoparticles and used for resolution of 1,1,1-trifluoro-2-octanol. The effects of reaction conditions, such as solvent, temperature, water activity and type of acyl donor were investiga
Highly enantioselective transfer hydrogenation of fluoroalkyl ketones
Sterk, Damjan,Stephan, Michel,Mohar, Barbara
, p. 5935 - 5938 (2007/10/03)
(Chemical Equation Presented) The asymmetric transfer hydrogenation of fluoroalkyl ketones mediated by [Ru(η6-arene)((S,S)-R 2NSO2DPEN)] catalysts using HCO2H-Et 3N afforded the corresponding alcohols
Two Classes of Enzymes of Opposite Stereochemistry in an Organism: One for Fluorinated and Another for Nonfluorinated Substrates
Matsuda, Tomoko,Harada, Tadao,Nakajima, Nobuyoshi,Itoh, Toshiyuki,Nakamura, Kaoru
, p. 157 - 163 (2007/10/03)
Reduction of methyl ketones by dried cells of Geotrichum candidum (APG4) afforded (S)-alcohols in excellent enantiomeric excess (ee), whereas the reduction of trifluoromethyl ketones gave the corresponding alcohols of the opposite configuration also in excellent ee. The replacement of the methyl moiety with a trifluoromethyl group alters both the bulkiness and the electronic properties, the effect of which on the stereoselectivity was examined. No inversion in stereochemistry was observed in the reduction of hindered ketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another with the opposite stereoselectivity catalyzed the reduction of trifluoromethyl ketones. Furthermore, both APG4 and the isolated enzyme were applied to the reduction of fluorinated ketones on a preparative scale, which resulted in the synthesis of chiral fluorinated alcohols with excellent ee.
Different stereochemistry for the reduction of trifluoromethyl ketones and methyl ketones catalyzed by alcohol dehydrogenase from Geotrichum
Nakamura, Kaoru,Matsuda, Tomoko,Itoh, Toshiyuki,Ohno, Atsuyoshi
, p. 5727 - 5730 (2007/10/03)
Reduction of trifluoromethyl ketones by a crude alcohol dehydrogenase from Geotrichum affords (S)-trifluoromethyl carbinols in excellent ee, whereas the reduction of methyl ketones gives the corresponding alcohols of the opposite configuration in excellent ee.
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
Ramachandran, P. Veeraraghavan,Gong, Baoqing,Brown, Herbert C.
, p. 41 - 46 (2007/10/02)
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.
Selective Reductions. 53. Asymmetric Reduction of α-Fluoromethyl Ketones with B-Chlorodiisopinocampheylborane or B-Isopinocampheyl-9-borabicyclononane. Combined Electronic and Steric Contributions to the Enantiocontrol Process
Ramachandran, P. Veeraraghavan,Teodorovic, Aleksandar V.,Gong, Baoqing,Brown, Herbert C.
, p. 1075 - 1086 (2007/10/02)
A systematic study of the asymmetric reduction of aryl and alkyl α-fluoroalkyl ketones with (-)-diisopinocampheylchloroborane ((-)-DIP-Chloride, 1) and (-)-B-isopinocampheyl-9-borabicyclononane (R-Alpine-Borane, 2) has been made.In the case of reagent 1, the direction of asymmetric induction in the chiral reduction of aryl trifluoromethyl ketones differs from that of the corresponding mono- and difluoromethyl ketones.For example, while 2-fluoro, and 2,2-difluoroacetophenones are reduced with 1 to the R-alcohols in 95percent and 85percent ee, respectively, 2,2,2-trifluoroacetophenone is reduced, under neat conditions at room temperature, to the S-alcohol in 90percent ee.Though DIP-Chloride reduces unhindered prochiral dialkyl ketones in poor ee, alkyl α-fluoroalkyl ketones are reduced in improved ee depending on the number of α-fluorine atoms present in the ketone.While monofluoromethyl ketones provide moderate ee in the R-isomer, the di- and trifluoromethyl ketones are reduced in moderate to excellent ee in the opposite isomer.For example, 1-fluoro-2-octanone is reduced in 40percent ee (R), whereas 1,1-difluoro- and 1,1,1-trifluoro-2-octanone are reduced in 32percent (S), and 91percent ee (S), respectively.In the case of the asymmetric reduction of the above series of ketones with 2, the results are different.There is no change in the direction of chiral induction in the reduction of α-fluoroacetophenones with 2. 2-Fluoroacetophenone and 2,2-difluoroacetophenone are reduced with 2 to the R-alcohol in 89percent and 97percent ee, respectively.The reaction of 2,2,2-trifluoroacetophenone is very slow, only 90percent complete in 45 d, and provides the R-alcohol in 32percent ee.In contrast, while 1-fluoro- and 1,1-difluoro-2-octanone are reduced by 2 in 65percent (R) and 50percent ee (R), respectively, 1,1,1-trifluoro-2-octanone is reduced in 60percent ee (S), raising the question of which factors other than the steric size of the trifluoromethyl group, control the enantioselectivity of these reductions.The effect of steric versus electronic influence in such chiral reductions is discussed.
Stereoselective Synthesis of Fluorinated Materials Catalyzed by an Antibody
Kitazume, Tomoya,Lin, Jenq Tain,Takeda, Mitsunori,Yamazaki, Takashi
, p. 2123 - 2126 (2007/10/02)
A monoclonal antibody, elicited by a transition-state analogue for the hydrolysis of fluorinated esters, acted as an enzymelike catalyst for the preparation of chiral fluorinated compounds. The syntheses of (R)- or (S)-1-(fluoroalkyl)alkanols and an allyl
