321-37-9Relevant academic research and scientific papers
Highly enantioselective construction of CF3-bearing all-carbon quaternary stereocenters: Hiral spiro-fused bisoxazoline ligands with 1,1′-binaphthyl sidearm for asymmetric Michael-type Friedel-Crafts reaction
Bao, Robert Li-Yuan,Fu, Kang,Shi, Lei
supporting information, (2021/11/27)
A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was prepared. The developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields (up to 99%) and good to excellent enantioselectivies (up to > 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indole from the Re-face of β-CF3-β-disubstituted nitroalkene was favorable.
Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system
Fujihira, Yamato,Liang, Yumeng,Ono, Makoto,Hirano, Kazuki,Kagawa, Takumi,Shibata, Norio
supporting information, p. 431 - 438 (2021/03/20)
A straightforward method that enables the formation of biologically attractive trifluoromethyl ketones from readily available methyl esters using the potent greenhouse gas fluoroform (HCF3, HFC-23) was developed. The combination of fluoroform and KHMDS in triglyme at ?40 °C was effective for this transformation, with good yields as high as 92%. Substrate scope of the trifluoromethylation procedure was explored for aromatic, aliphatic, and conjugated methyl esters. This study presents a straightforward trifluoromethylation process of various methyl esters that convert well to the corresponding trifluoromethyl ketones. The tolerance of various pharmacophores under the reaction conditions was also explored.
A Hammett Study of Clostridium acetobutylicum Alcohol Dehydrogenase (CaADH): An Enzyme with Remarkable Substrate Promiscuity and Utility for Organic Synthesis
Berkowitz, David B.,Kudalkar, Gaurav P.,Lee, Joshua D.,Tiwari, Virendra K.
supporting information, p. 237 - 247 (2020/02/18)
Described is a physical organic study of the reduction of three sets of carbonyl compounds by the NADPH-dependent enzyme Clostridium acetobutylicum alcohol dehydrogenase (CaADH). Previous studies in our group have shown this enzyme to display broad substrate promiscuity, yet remarkable stereochemical fidelity, in the reduction of carbonyl compounds, including α-, β- and γ-keto esters (d -stereochemistry), as well as α,α-difluorinated-β-keto phosphonate esters (l -stereochemistry). To better mechanistically characterize this promising dehydrogenase enzyme, we report here the results of a Hammett linear free-energy relationship (LFER) study across three distinct classes of carbonyl substrates; namely aryl aldehydes, aryl β-keto esters and aryl trifluoromethyl ketones. Rates are measured by monitoring the decrease in NADPH fluorescence at 460 nm with time across a range of substrate concentrations for each member of each carbonyl compound class. The resulting v 0 versus [S] data are subjected to least-squares hyperbolic fitting to the Michaelis-Menton equation. Hammett plots of log(V max) versus σ X yield the following Hammett parameters: (i) for p -substituted aldehydes, ρ = 0.99 ± 0.10, ρ = 0.40 ± 0.09; two domains observed, (ii) for p -substituted β-keto esters ρ = 1.02 ± 0.31, and (iii) for p -substituted aryl trifluoromethyl ketones ρ = -0.97 ± 0.12. The positive sign of ρ indicated for the first two compound classes suggests that the hydride transfer from the nicotinamide cofactor is at least partially rate-limiting, whereas the negative sign of ρ for the aryl trifluoromethyl ketone class suggests that dehydration of the ketone hydrate may be rate-limiting for this compound class. Consistent with this notion, examination of the 13 C NMR spectra for the set of p -substituted aryl trifluo romethyl ketones in 2percent aqueous DMSO reveals significant formation of the hydrate (gem -diol) for this compound family, with compounds bearing the more electron-withdrawing groups showing greater degrees of hydration. This work also presents the first examples of the CaADH-mediated reduction of aryl trifluoromethyl ketones, and chiral HPLC analysis indicates that the parent compound α,α,α-trifluoroacetophenone is enzymatically reduced in 99percent ee and 95percent yield, providing the (S)-stereoisomer, suggesting yet another compound class for which this enzyme displays high enantioselectivity.
Palladium-catalyzed fluoroacylation of (Hetero)arylboronic acid with fluorothioacetates at ambient temperature
Ban, Shu-Rong,Cao, Ya-Fang,Dai, Hui-Xiong,Wang, Xing,Xu, Hui,Yi, Xing
supporting information, (2020/03/23)
A palladium-catalyzed fluoroacylation of (hetero)aryl boronic acid with the fluorothioacetates is described at ambient temperature. A variety of aryl, and heteroaryl boronic acids are compatible in the reaction, affording the corresponding fluoroalkyl ketones in moderate to good yields. Further late-stage di-, and trifluoroacylation of drug molecule clofibrate and estrone demonstrated the synthetic practicability of this protocol.2009 Elsevier Ltd. All rights reserved.
Fluoroform: an Efficient Precursor for the Trifluoromethylation of Aromatic Esters by Sodium Diisopropylamide with Trialkylamines
Han, Zhaomeng,Chen, Sihan,Tu, Yongjun,Lian, Xiongdong,Li, Gongyong
supporting information, p. 4658 - 4661 (2019/08/07)
The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylation reactions. It is believed to be incompatible with Na+ cation due to the strong Na–F bond. However, herein we demonstrate that it could be prepared for the first time. Trialkylamines can be used as cation chelating agents to stabilize the isolated –CF3 ion to realize trifluoromethylation reaction. With this strategy, trifluoromethyl aromatic ketones could be effectively synthesized from fluoroform and aromatic esters with diisopropyl aminosodium (NaDA) and trialkylamines.
Visible light-promoted umpolung coupling of aryl tri-/difluoroethanones with 2-alkenylpyridines
Xu, Xiao,Min, Qing-Qiang,Li, Na,Liu, Feng
supporting information, p. 11017 - 11020 (2018/10/08)
Tertiary alcohols bearing a trifluoromethyl group are of considerable medicinal interest. Using an umpolung strategy, we herein report the first intermolecular reductive cross-coupling of aryl tri-/difluoroethanones with 2-alkenylpyridines with the aid of a Br?nsted acid catalyst upon visible-light irradiation. This metal-free reaction is operationally simple and performed at ambient temperature, allowing access to desired tertiary alcohols with tri-/difluoromethyl groups in moderate to excellent yields. The commercially available and easily handled Hantzsch ester effectively serves as an electron donor, as well as a hydrogen atom source.
Enantioselective Synthesis of Trifluoromethyl α,β-Unsaturated δ-Lactones via Vinylogous Aldol-Lactonization Cascade
Crotti, Simone,Di Iorio, Nicola,Mazzanti, Andrea,Righi, Paolo,Bencivenni, Giorgio
, p. 12440 - 12448 (2018/10/09)
The novel vinylogous aldol-lactonization cascade of alkylidene oxindole with trifluoromethyl ketones is presented. The reaction, catalyzed by a bifunctional tertiary amine, provides an efficient application of the vinylogous reactivity of alkylidene oxindoles for the preparation of enantioenriched trifluoromethylated α,β-unsaturated δ-lactones.
Radical C(sp2)-H Trifluoromethylation of Aldehydes in Aqueous Solution
Zhang, Pei,Shen, Haigen,Zhu, Lin,Cao, Weiguo,Li, Chaozhong
supporting information, p. 7062 - 7065 (2018/11/21)
The copper-mediated C(sp2)-H trifluoromethylation of aldehydes is described. The reaction of aldehydes with (bpy)Cu(CF3)3, Et3SiH, and K2S2O8 in aqueous acetone at room temperatu
MgCl2-catalyzed trifluoromethylation of carbonyl compounds using (trifluoromethyl)trimethylsilane as the trifluoromethylating agent
Cui, Bin,Sun, Hui,Xu, Yibo,Duan, Lili,Li, Yue-Ming
, p. 6754 - 6762 (2017/11/09)
Using (trifluoromethyl)trimethylsilane (TMSCF3) as the trifluoromethylating agent, MgCl2-catalyzed trifluoromethylation of carbonyl compounds proceeded readily at room temperature. In the presence of 10 mol% of MgCl2, a variety of carbonyl substrates such as aliphatic/aromatic aldehydes, acyclic/cyclic ketones and esters could be trifluoromethylated in DMF, giving the corresponding trimethylsilyl ethers (ketals) in up to 93% isolated yields. Trifluoromethylketones could be readily obtained after hydrolysis of the trimethylsilyl ketals. The reactions could tolerate air and moisture, and the use of oxygen and moisture-free conditions was not required.
Asymmetric Construction of Pyrrolidines Bearing a Trifluoromethylated Quaternary Stereogenic Center via CuI-Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with β-CF3-β,β-Disubstituted Nitroalkenes
Tang, Li-Wei,Zhao, Bao-Jing,Dai, Li,Zhang, Man,Zhou, Zhi-Ming
supporting information, p. 2470 - 2477 (2016/09/13)
A direct and convenient method has been developed for the synthesis of optically active pyrrolidines bearing a quaternary stereogenic center containing a CF3 group at the C-3 position of the pyrrolidine ring. The synthesis system, CuI/Si-FOXAP-catalyzed exo-selective 1,3-dipolar cycloaddition of azomethine ylides with β-CF3-β,β-disubstituted nitroalkenes, provides pyrrolidines with high diastereoselectivities (up to >98:2 d.r.) and excellent enantioselectivities (up to >99.9 ee) and performs well for a broad scope of substrates under mild conditions.
