146801-29-8Relevant articles and documents
Simple access to novel β-hydroxy-β-trifluoromethyl imines
Barten, Jan Alexander,Funabiki, Kazumasa,R?schenthaler, Gerd-Volker
, p. 105 - 109 (2002)
Selected imines reacted with three different trifluoromethyl group-containing ketones in a non-catalyzed manner at ambient temperature to give the corresponding β-hydroxy-β-trifluoromethyl imines in good to excellent yields. With 1,1,1-trifluoroacetone a
A Catalytic Strategy for α,ω-Functionalization: NHC-Mediated Fragmentation/Umpolung Cascades to Access Hydroxytrifluoromethyl Ynones and Allenones
Selg, Christoph,Kraft, Fabian B.,Welcke, Linda,Zeitler, Kirsten
, p. 3750 - 3755 (2019)
Herein we report an unprecedented, convenient NHC-catalyzed one-pot cascade reaction to afford α,ω-difunctionalized hydroxytrifluoromethyl alkynones and allenones in a single step. The critical fragile aliphatic aldehydes are introduced by a base-mediated in situ Grob-type fragmentation of their corresponding latent cyclic vinylogous hemiacetal triflate (VHAT) and γ-hydroxy vinyl triflate (GHVT) precursors, avoiding typical problems and losses upon isolation. The ′demasked′ aldehydes are subsequently trapped by NHC-catalyzed umpolung and further metal-free C?C-cross-coupling to access a broad scope of terminally modified alkynyl or allenyl aliphatic, aromatic and heteroaromatic trifluoromethyl ketones as multifunctionalized, high-value building blocks for advanced synthetic applications. Additional synthetic utility of this approach is demonstrated with the possibility for asymmetric variants using chiral NHC-catalysts.
Combining prolinamides with 2-pyrrolidinone: Novel organocatalysts for the asymmetric aldol reaction
Vlasserou, Ismini,Sfetsa, Maria,Gerokonstantis, Dimitrios-Triantafyllos,Kokotos, Christoforos G.,Moutevelis-Minakakis, Panagiota
, p. 2338 - 2349 (2018/04/06)
Peptides and especially prolinamides have been identified as excellent organocatalysts for the aldol reaction. The combination of prolinamides with derivatives bearing the 2-pyrrolidinone scaffold, deriving from pyroglutamic acid, led to the identification of novel organocatalysts for the intermolecular asymmetric aldol reaction. The new hybrids were tested both in organic and aqueous media. Among the compounds tested, 22 afforded the best results in petroleum ether, while 25 afforded the products in brine in high yields and selectivities. Then, various ketones and aldehydes were utilized and the products of the aldol reaction were obtained in high yields (up to 100%) with excellent diastereo- (up to 97:3 dr) and enantioselectivities (up to 99% ee).
Screening, Molecular Cloning, and Biochemical Characterization of an Alcohol Dehydrogenase from Pichia pastoris Useful for the Kinetic Resolution of a Racemic β-Hydroxy-β-trifluoromethyl Ketone
Bulut, Dalia,Hummel, Werner,Gr?ger, Harald,Duangdee, Nongnaphat,Berkessel, Albrecht
, p. 1349 - 1358 (2016/12/24)
The stereoselective synthesis of chiral 1,3-diols with the aid of biocatalysts is an attractive tool in organic chemistry. Besides the reduction of diketones, an alternative approach consists of the stereoselective reduction of β-hydroxy ketones (aldols). Thus, we screened for an alcohol dehydrogenase (ADH) that would selectively reduce a β-hydroxy-β-trifluoromethyl ketone. One potential starting material for this process is readily available by aldol addition of acetone to 2,2,2-trifluoroacetophenone. Over 200 strains were screened, and only a few yeast strains showed stereoselective reduction activities. The enzyme responsible for the reduction of the β-hydroxy-β-trifluoromethyl ketone was identified after purification and subsequent MALDI-TOF mass spectrometric analysis. As a result, a new NADP+-dependent ADH from Pichia pastoris (PPADH) was identified and confirmed to be capable of stereospecific and diastereoselective reduction of the β-hydroxy-β-trifluoromethyl ketone to its corresponding 1,3-diol. The gene encoding PPADH was cloned and heterologously expressed in Escherichia coli BL21(DE3). To determine the influence of an N- or C-terminal His-tag fusion, three different recombinant plasmids were constructed. Interestingly, the variant with the N-terminal His-tag showed the highest activity; consequently, this variant was purified and characterized. Kinetic parameters and the dependency of activity on pH and temperature were determined. PPADH shows a substrate preference for the reduction of linear and branched aliphatic aldehydes. Surprisingly, the enzyme shows no comparable activity towards ketones other than the β-hydroxy-β-trifluoromethyl ketone.
Highly Enantioselective Construction of Fluoroalkylated Quaternary Stereocenters via Organocatalytic Dehydrated Mannich Reaction of Unprotected Hemiaminals with Ketones
Zhang, Sheng,Li, Lijun,Hu, Yanbin,Li, Yanan,Yang, Yu,Zha, Zhenggen,Wang, Zhiyong
supporting information, p. 5036 - 5039 (2015/11/03)
A general organocatalytic asymmetric dehydrated Mannich reaction of fluoroalkyl hemiaminals with ketones is reported. In this Mannich reaction, previously less explored aryl ketones showed great reactivity. By virtue of this efficient method, a wide range of biologically active β-amino ketones were directly obtained. More importantly, two different intermediates involved in the reaction were detected and identified by 19F NMR and HRMS analysis. Furthermore, the synthetic utility of the products was demonstrated by the synthesis of the biologically active fluoroalkyl β-amino alcohols.
Direct aldol reaction of trifluoromethyl ketones with ketones catalyzed by Et2Zn and secondary amines
Sasaki, Shigeru,Kikuchi, Kasumi,Yamauchi, Takayasu,Higashiyama, Kimio
supporting information; experimental part, p. 1431 - 1434 (2011/08/03)
The direct catalytic aldol reaction of trifluoromethyl ketones with ketones has been accomplished. The reaction was achieved in the presence of 10 mol% Et2Zn and N,N-dimethylethylenediamine at ambient temperature to give the expected aldol-type
Novel reduction of perfluoroalkyl ketones with lithium alkoxides
Sokeirik, Yasser S.,Sato, Kazuyuki,Omote, Masaaki,Ando, Akira,Kumadaki, Itsumaro
, p. 150 - 152 (2008/09/17)
The reaction of tert-butyl N-(2-bromophenyl)carbamate (1) with ethyl perfluorooctanoate in the presence of tert-butyllithium did not give the desired N-(2-perfluorooctanoylphenyl)carbamate (3) but gave 1-hydroxy-1H-perfluorooctyl compound (4), which was supposed to be formed by the reduction of 3. A similar reaction of 2,2,2-trifluoroacetophenone with tert-butyllithium did not gave any reduction product. Detailed investigation showed that lithium ethoxide worked as the reducing agent of this abnormal reduction. By the reaction of lithium isopropoxide, an aldol product from 2,2,2-trifluoroacetophenone with acetone was isolated, while perfluoroheptyl or perfluoropropyl phenyl ketones were reduced by this alkoxide in a high yield without formation of the aldol adduct.
Aldol condensation of trifluoroacetophenone and acetone: Testing a prediction
Guthrie, J. Peter,Barker, Jonathan A.
, p. 6698 - 6703 (2007/10/03)
Rate and equilibrium constants have been determined for both stages of the aldol condensation of acetone with trifluoroacetophenone. The extensive hydration of trifluoroacetophenone and the acid dissociation of the hydrate complicated the kinetic analysis. Dehydration of the intermediate ketol leads to two enones which equilibrate in base more rapidly than they undergo hydration to the ketol. This is consistent with interconversion via the enolate of the ketol, which loses OH- faster than it undergoes C-protonation. The rate constant determined for the aldol addition step is in satisfactory agreement with the value predicted from a Marcus correlation (J. Am. Chem. Sec. 1991, 113, 7249-7255).
KETONE-KETONE CONDENSATION WITH THE PARTICIPATION OF POLYHALOALKYL PHENYL KETONES
Sosnovskikh, V. Ya.,Ovsyannikov, I. S.,Aleksandrova, I. A.
, p. 420 - 426 (2007/10/02)
In the cross condensation of polyhaloalkyl phenyl ketones with methyl ketones in the presence of (ethylphenylamino)magnesium or (diethylamino)magnesium bromide or lithium hydride β-hydroxy ketones are formed, and the dehydration of these under the action
