7100-97-2Relevant academic research and scientific papers
Manganese(III) 5,15-diazaporphyrins: Synthesis, properties, and catalytic use for benzylic C-H fluorination
Mori, Shiho,Nishimura, Tsubasa,Shinokubo, Hiroshi,Miyake, Yoshihiro
, p. 991 - 996 (2021/08/23)
Fluorination of sp3 C-H bonds has attracted considerable attention as a promising method for the synthesis of organofluorine compounds. Manganese porphyrins have been extensively investigated as catalysts in the fluorination of saturated sp3 C-H bonds. Recently, we have found that iron(III) 5,15-diazaporphyrins, which are porphyrin analogues with imine-type sp2-hybridized nitrogen atoms at the meso-positions, showed high catalytic performance in the oxidation of sp3 C-H bonds. Here we disclose the synthesis, structure, and electronic properties of manganese(III) 5,15-diazaporphyrins. We also demonstrate the catalysis of chloromanganese(III) 5,15-diazaporphyrins for benzylic fluorination.
Insertion of Diazo Esters into C-F Bonds toward Diastereoselective One-Carbon Elongation of Benzylic Fluorides: Unprecedented BF3Catalysis with C-F Bond Cleavage and Re-formation
Wang, Fei,Nishimoto, Yoshihiro,Yasuda, Makoto
, p. 20616 - 20621 (2021/11/23)
Selective transformation of C-F bonds remains a significant goal in organic chemistry, but C-F insertion of a one-carbon-atom unit has never been established. Herein we report the BF3-catalyzed formal insertion of diazo esters as one-carbon-atom sources into C-F bonds to accomplish one-carbon elongation of benzylic fluorides. A DFT calculation study revealed that the BF3 catalyst could contribute to both C-F bond cleavage and re-formation. This elongation provided α-fluoro-α,β-diaryl esters with a high level of diastereoselectivity. Various benzylic fluorides and diazo esters were applicable. The synthetic utility of this method was demonstrated by the synthesis of a fluoro analogue of a compound that is used as a transient receptor and potential canonical channel inhibitor.
Fluorinating agent and synthesis method thereof
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Paragraph 0065-0081, (2020/09/16)
The invention discloses a fluorinating agent, and also discloses a preparation method of the fluorinating agent, wherein an amide corresponding to the structural formula of the product reacts with a halogenating agent to obtain corresponding alpha, alpha-dihaloamine, and the alpha, alpha-dihaloamine reacts with a fluoride to obtain the corresponding fluorinating agent. The fluorinating agent has the advantages of being stable in storage and capable of fluorinating hydroxyl with high yield, the preparation method is simple, the adopted raw materials are easy to obtain, the synthesis yield is high, and the fluorinating efficiency of the obtained product is high.
Deoxyfluorination with CuF2: Enabled by Using a Lewis Base Activating Group
Bode, Bela E.,Chabbra, Sonia,Champion, Sue,Dawson, Daniel M.,Sood, D. Eilidh,Sutherland, Andrew,Watson, Allan J. B.
supporting information, p. 8460 - 8463 (2020/04/10)
Deoxyfluorination is a primary method for the formation of C?F bonds. Bespoke reagents are commonly used because of issues associated with the low reactivity of metal fluorides. Reported here is the development of a simple strategy for deoxyfluorination, using first-row transition-metal fluorides, and it overcomes these limitations. Using CuF2 as an exemplar, activation of an O-alkylisourea adduct, formed in situ, allows effective nucleophilic fluoride transfer to a range of primary and secondary alcohols. Spectroscopic investigations have been used to probe the origin of the enhanced reactivity of CuF2. The utility of the process in enabling 18F-radiolabeling is also presented.
Copper-Catalyzed Functionalization of Benzylic C-H Bonds with N-Fluorobenzenesulfonimide: Switch from C-N to C-F Bond Formation Promoted by a Redox Buffer and Br?nsted Base
Buss, Joshua A.,Golden, Dung L.,Stahl, Shannon S.,Vasilopoulos, Aristidis
supporting information, p. 5749 - 5752 (2020/10/02)
A copper catalyst in combination with N-fluorobenzenesulfonimide (NFSI) has been reported to functionalize benzylic C-H bonds to the corresponding benzylic sulfonimides via C-N coupling. Here, we reported a closely related Cu-catalyzed method with NFSI that instead leads to C-F coupling. This switch in selectivity arises from changes to the reaction conditions (Cu/ligand ratio, temperature, addition of base) and further benefits from inclusion of MeB(OH)2 in the reaction. MeB(OH)2 is shown to serve as a "redox buffer"in the reaction, responsible for rescuing inactive Cu(II) for continued promotion of fluorination reactivity.
C(sp3)-H Fluorination with a Copper(II)/(III) Redox Couple
Bower, Jamey K.,Cypcar, Andrew D.,Henriquez, Brenda,Stieber, S. Chantal E.,Zhang, Shiyu
supporting information, p. 8514 - 8521 (2020/05/28)
Despite the growing interest in the synthesis of fluorinated organic compounds, few reactions are able to incorporate fluoride ions directly into alkyl C-H bonds. Here, we report the C(sp3)-H fluorination reactivity of a formally copper(III) fluoride complex. The C-H fluorination intermediate, LCuF, along with its chloride and bromide analogues, LCuCl and LCuBr, were prepared directly from halide sources with a chemical oxidant and fully characterized with single-crystal X-ray diffraction, X-ray absorption spectroscopy, UV-vis spectroscopy, and 1H nuclear magnetic resonance spectroscopy. Quantum chemical calculations reveal significant halide radical character for all complexes, suggesting their ability to initiate and terminate a C(sp3)-H halogenation sequence by sequential hydrogen atom abstraction (HAA) and radical capture. The capability of HAA by the formally copper(III) halide complexes was explored with 9,10-dihydroanthracene, revealing that LCuF exhibits rates 2 orders of magnitude higher than LCuCl and LCuBr. In contrast, all three complexes efficiently capture carbon radicals to afford C(sp3)-halogen bonds. Mechanistic investigation of radical capture with a triphenylmethyl radical revealed that LCuF proceeds through a concerted mechanism, while LCuCl and LCuBr follow a stepwise electron transfer-halide transfer pathway. The capability of LCuF to perform both hydrogen atom abstraction and radical capture was leveraged to enable fluorination of allylic and benzylic C-H bonds and α-C-H bonds of ethers at room temperature.
Fast Hydrocarbon Oxidation by a High-Valent Nickel–Fluoride Complex
Lovisari, Marta,McDonald, Aidan R.,Mondal, Prasenjit,Twamley, Brendan
supporting information, p. 13044 - 13050 (2020/06/05)
In the search for highly reactive oxidants we have identified high-valent metal–fluorides as a potential potent oxidant. The high-valent Ni–F complex [NiIII(F)(L)] (2, L=N,N′-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamidate) was prepared from [NiII(F)(L)]? (1) by oxidation with selectfluor. Complexes 1 and 2 were characterized by using 1H/19F NMR, UV-vis, and EPR spectroscopies, mass spectrometry, and X-ray crystallography. Complex 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic data and products analysis demonstrate a hydrogen atom transfer mechanism of oxidation. The rate constant determined for the oxidation of 9,10-dihydroanthracene (k2=29 m?1 s?1) compared favorably with the most reactive high-valent metallo-oxidants. Complex 2 displayed reaction rates 2000–4500-fold enhanced with respect to [NiIII(Cl)(L)] and also displayed high kinetic isotope effect values. Oxidative hydrocarbon and phosphine fluorination was achieved. Our results provide an interesting direction in designing catalysts for hydrocarbon oxidation and fluorination.
Copper-Catalyzed C-H Fluorination/Functionalization Sequence Enabling Benzylic C-H Cross Coupling with Diverse Nucleophiles
Buss, Joshua A.,Golden, Dung L.,Stahl, Shannon S.,Vasilopoulos, Aristidis
supporting information, (2020/08/24)
Site-selective transformation of benzylic C-H bonds into diverse functional groups is achieved via Cu-catalyzed C-H fluorination with N-fluorobenzenesulfonimide (NFSI), followed by substitution of the resulting fluoride with various nucleophiles. The benzyl fluorides generated in these reactions are reactive electrophiles in the presence of hydrogen-bond donors or Lewis acids, allowing them to be used without isolation in C-O, C-N, and C-C coupling reactions.
Transition metal-free cross-dehydrogenative arylation of unactivated benzylic C-H bonds
Spencer, Andrew R. A.,Grainger, Rachel,Panigrahi, Adyasha,Lepper, Thomas J.,Bentkowska, Katarzyna,Larrosa, Igor
supporting information, p. 14479 - 14482 (2020/12/01)
The cross-dehydrogenative arylation of benzylic C-H bonds with arenes provides straightforward access to synthetically useful 1,1-diarylmethanes, from readily available starting materials. Current approaches suffer from limited substrate scope, requirement for large excesses of alkyl arene and/or non-trivial reaction set up. We report a transition metal-free cross-dehydrogenative arylation of benzylic C-H bonds using alkyl benzene derivatives and electron-rich arenes as coupling partners. The method proceeds through the in situ generation of a reactive benzyl fluoride intermediate which then reacts with the nucleophilic arene. The reaction tolerates a wide variety of functional groups including unprotected polar functionality and has been applied to the late-stage benzylation of several biologically relevant molecules.
Expanding the repertoire of cyclopropenium ion phase transfer catalysis: Benzylic fluorination
Dempsey, Katie,Mir, Roya,Smajlagic, Ivor,Dudding, Travis
supporting information, p. 3507 - 3511 (2018/05/25)
The application of cyclopropenium ion as a phase transfer catalyst for benzylic fluorination in high yields is reported. Integral to the mechanisms of these fluorination reactions was the role of in situ derived cyclopropenium fluoride complexes, the existence of which was supported by 1H, 19F NMR and UV–Vis spectroscopy. Density functional theory calculations were applied to gain insight into the mechanism of these reactions.
