17556-42-2Relevant articles and documents
Synthesis and synthetic applications of (4-hydroxyphenyl)perfluoroalkylmethanols
Terashima, Kyu,Kawasaki-Takasuka, Tomoko,Minami, Ichiro,Yamazaki, Takashi
, (2021/12/03)
Development of the convenient method for the synthesis of (hydroxyphenyl)perfluoro-alkylmethanols was achieved by the Meerwein-Ponndorf-Verley (MPV) type reduction of the in situ-generated perfluoroalkylated ketones as the key step. The benzylic OH group of the resultant alcohols was successfully converted to H or Rf(CH2)nO by way of the corresponding chlorides, this transformation being not easy by any other methods.
Fluorine-18 labelled Ruppert-Prakash reagent ([18F]Me3SiCF3) for the synthesis of 18F-trifluoromethylated compounds
Pees, Anna,Vosjan, Maria J.W.D,Vasdev, Neil,Windhorst, Albert D.,Vugts, Danielle J.
supporting information, p. 5286 - 5289 (2021/06/06)
This article describes the first synthesis and application of fluorine-18 labelled Ruppert-Prakash reagent [18F]Me3SiCF3. [18F]Me3SiCF3 was synthesized from [18F]fluoroform with radiochemical yields of 85-95% and radiochemical purities of >95% within 20 m
Photoredox-Catalyzed Ring-Opening Addition Reaction between Benzyl Bromides and Cyclic Ethers
Gu, Yucheng,Hu, Jinbo,Kuang, Cuiwen,Ni, Chuanfa
, (2021/12/24)
A novel nucleophilic reaction between cyclic ethers and benzyl bromides is achieved under photoredox catalysis. The reaction proceeds through a single-electron-transfer (SET) pathway rather than a common SN2 mechanism. By two steps of reduction and oxidation, a benzyl bromide heterolyzes to give a carbocation and bromide ion under mild conditions, and then a cyclic ether captures both the carbocation and bromide ion to afford the addition product.
Structure-function relationships in aryl diazirines reveal optimal design features to maximize C-H insertion
Bi, Liting,DiLabio, Gino A.,Musolino, Stefania F.,Pei, Zhipeng,Wulff, Jeremy E.
, p. 12138 - 12148 (2021/09/28)
Diazirine reagents allow for the ready generation of carbenes upon photochemical, thermal, or electrical stimulation. Because carbenes formed in this way can undergo rapid insertion into any nearby C-H, O-H or N-H bond, molecules that encode diazirine functions have emerged as privileged tools in applications ranging from biological target identification and proteomics through to polymer crosslinking and adhesion. Here we use a combination of experimental and computational methods to complete the first comprehensive survey of diazirine structure-function relationships, with a particular focus on thermal activation methods. We reveal a striking ability to vary the activation energy and activation temperature of aryl diazirines through the rational manipulation of electronic properties. Significantly, we show that electron-rich diazirines have greatly enhanced efficacy toward C-H insertion, under both thermal and photochemical activation conditions. We expect these results to lead to significant improvements in diazirine-based chemical probes and polymer crosslinkers.
Synthesis of Unsymmetric Triarylmethanes Bearing CF 3-Substituted All-Carbon Quaternary Stereocenters: 1,6-Arylation of δ-Trifluo romethyl Substituted para -Quinone Methides
Ma, Yingang,Pang, Jingxiang,Pan, Xiaoguang,Ma, Shutao,Liu, Xigong,Liu, Lei
supporting information, p. 1619 - 1622 (2020/09/15)
Pre-synthesized δ-CF 3-δ-aryl-disubstituted para -quinone methides bearing δ-substituents were identified as isolable and storable substrates for 1,6-arylation reactions. A broad range of electron-rich arenes and heteroarenes participated in the arylation process, furnishing a wide array of unsymmetrical CF 3-substituted triarylmethanes in high efficiency. The mild and expeditious protocol exhibited broad scopes of both arene and para -quinone methide components.
Generation of Carbocations under Photoredox Catalysis: Electrophilic Aromatic Substitution with 1-Fluoroalkylbenzyl Bromides
Gu, Yucheng,Hu, Jinbo,Kuang, Cuiwen,Ni, Chuanfa,Xie, Qiqiang,Zhou, Xin
supporting information, (2020/11/13)
A novel Friedel-Crafts-type alkylation of arenes to access valuable 1-fluoroalkyl-1,1-biaryl compounds is established under mild conditions. The key to success is the efficient generation of a destabilized benzylic carbocation intermediate via two consecutive single-electron transfer processes by virtue of visible-light photoredox catalysis. This unique activation pattern avoids using strong Lewis acids and high temperatures that are required for generation of destabilized carbocations in traditional Friedel-Crafts reactions. This protocol demonstrates the first example of photoredox-catalyzed heterolysis of electronically deactivated benzylic C-Br bonds for the formation of destabilized carbocation intermediates.
One-Pot Successive Turbo Grignard Reactions for the Facile Synthesis of α-Aryl-α-Trifluoromethyl Alcohols
Kani, Ryunosuke,Inuzuka, Toshiyasu,Kubota, Yasuhiro,Funabiki, Kazumasa
supporting information, p. 4487 - 4493 (2020/06/01)
A novel straightforward one-pot methodology for two successive turbo Grignard reagent (iPrMgCl·LiCl) reactions, was developed for a facile synthesis of α-aryl-α-trifluoromethyl alcohols, motifs of value in pharmaceutical chemistry. The method displayed broad functional group tolerance, including reducible groups. Dual roles of iPrMgCl·LiCl were exploited in the tandem reaction with commercially available iodoarenes or iodoheteroarenes and 2,2,2-trifluoroethyl trifluoroacetate. The process encompasses three successive reactions in a one-pot process: the iPrMgCl·LiCl-mediated iodine/magnesium-exchange reaction of iodoarenes or iodoheteroarenes; nucleophilic addition of various generated aryl or heteroarylmagnesium reagents to 2,2,2-trifluoroethyl trifluoroacetate; and the reduction of in-situ generated aryl trifluoromethyl ketones with iPrMgCl·LiCl, to produce the corresponding α-aryl or α-heteroaryl-α-trifluoromethyl alcohols bearing various substituents, including reducible functional groups in good to excellent yields.
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.
, 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.
Asymmetric Hydrogenation of Aryl Perfluoroalkyl Ketones Catalyzed by Rhodium(III) Monohydride Complexes Bearing Josiphos Ligands
Brüning, Fabian,Nagae, Haruki,K?ch, Daniel,Mashima, Kazushi,Togni, Antonio
supporting information, p. 10818 - 10822 (2019/07/31)
The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2, Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis (up to 99 % ee) of chiral secondary alcohols with perfluoroalkyl groups. This system does not require an activating base for the hydrogenation of 2,2,2-trifluoroacetophenones. Additionally, the enantioselective C=O hydrogenations of 2-phenyl-3-(haloacetyl)-indoles, a class of privileged structures in medicinal chemistry, is reported for the first time.
One-Pot and Reducible-Functional-Group-Tolerant Synthesis of α-Aryl- and α-Heteroaryl-α-Trifluoromethyl Alcohols via Tandem Trifluoroacetylation and MPV Type Reduction
Funabiki, Kazumasa,Hayakawa, Ayaka,Kani, Ryunosuke,Inuzuka, Toshiyasu,Kubota, Yashuhiro
, p. 5978 - 5984 (2019/08/30)
We have developed a new one-pot synthesis of α-aryl- and α-heteroaryl-α-trifluoromethyl alcohols carrying not only arenes with electron-withdrawing groups but also electron-deficient nitrogen-containing heteroarenes, which are of increasing interest becau
