51443-95-9Relevant academic research and scientific papers
Open-Shell Fluorination of Alkyl Bromides: Unexpected Selectivity in a Silyl Radical-Mediated Chain Process
Lovett, Gabrielle H.,Chen, Shuming,Xue, Xiao-Song,Houk,MacMillan, David W. C.
, p. 20031 - 20036 (2019/12/27)
We disclose a novel radical strategy for the fluorination of alkyl bromides via the merger of silyl radical-mediated halogen-atom abstraction and benzophenone photosensitization. Selectivity for halogen-atom abstraction from alkyl bromides is observed in the presence of an electrophilic fluorinating reagent containing a weak N-F bond despite the predicted favorability for Si-F bond formation. To probe this surprising selectivity, preliminary mechanistic and computational studies were conducted, revealing that a radical chain mechanism is operative in which kinetic selectivity for Si-Br abstraction dominates due to a combination of polar effects and halogen-atom polarizability in the transition state. This transition-metal-free fluorination protocol tolerates a broad range of functional groups, including alcohols, ketones, and aldehydes, which demonstrates the complementary nature of this strategy to existing fluorination technologies. This system has been extended to the generation of gem-difluorinated motifs which are commonly found in medicinal agents and agrochemicals.
Photoredox-catalyzed deoxyfluorination of activated alcohols with Selectfluor
González-Esguevillas, María,Miró, Javier,Jeffrey, Jenna L.,MacMillan, David W.C.
supporting information, p. 4222 - 4227 (2019/06/13)
Herein we disclose a deoxyfluorination of alcohols with an electrophilic fluorine source via visible-light photoredox catalysis. This radical-mediated C–F coupling is capable of fluorinating secondary and tertiary alcohols efficiently, complementing previously reported nucleophilic deoxyfluorination protocols.
A photocatalyzed aliphatic fluorination
Bloom, Steven,Knippel, James Levi,Lectka, Thomas
, p. 1175 - 1178 (2014/03/21)
We disclose a new approach to the catalysis of alkane fluorination employing ultraviolet light and a photosensitizer, 1,2,4,5-tetracyanobenzene (TCB). The process is efficient, mild, and operationally straightforward. We demonstrate reaction utility on a variety of substrates, from simple hydrocarbons to complex natural products. In a showcase example, we establish that the well-known photochemical rearrangement of α-santonin can be supplanted by a highly selective catalyzed fluorination. The Royal Society of Chemistry 2014.
Triethylborane-initiated radical chain fluorination: A synthetic method derived from mechanistic insight
Pitts, Cody Ross,Ling, Bill,Woltornist, Ryan,Liu, Ran,Lectka, Thomas
, p. 8895 - 8899 (2015/01/08)
We offer a mild, metal-free sp3 C-H fluorination alternative using Selectfluor and a substoichiometric amount of triethylborane.an established radical initiator in the presence of O2. This radical-chain-based synthetic method is particularly noteworthy as an offspring of the insight gained from a mechanistic study of copper-promoted aliphatic fluorination, constructively turning O2 from an enemy to an ally. Furthermore, BEt3/O2 is a preferred initiator in industrial processes, as it is economical, is low in toxicity, and lends way to easier workup.
Visible light-promoted metal-free sp3-C-H fluorination
Xia, Ji-Bao,Zhu, Chen,Chen, Chuo
supporting information, p. 11701 - 11704 (2015/05/20)
Photoexcited acetophenone can catalyze the fluorination of unactivated C(sp3)-H groups. While acetophenone, a colorless oil, only has a trace amount of absorption in the visible light region, its photoexcitation can be achieved by irradiation with light generated by a household compact fluorescent lamp (CFL). This operational simple method provides improved substrate scope for the direct incorporation of a fluorine atom into simple organic molecules. CFL-irradiation can also be used to promote certain classic UV-promoted photoreactions of colorless monoarylketones and enones/enals.
C-HALOGEN BOND FORMATION
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Paragraph 0139-0140; 0142-0144; 0151; 0163-0164, (2013/03/26)
Methods of halogenating a carbon containing compound having an sp3 C-H bond are provided. Methods of fluorinating a carbon containing compound comprising halogenation with Cl or Br followed by nucleophilic substitution with F are provided. Methods of direct oxidative C-H fluorination of a carbon containing compound having an sp3 C-H bond are provided. The halogenated products of the methods are provided.
Oxidative aliphatic C-H fluorination with fluoride ion catalyzed by a manganese porphyrin
Liu, Wei,Huang, Xiongyi,Groves, John T.,Cheng, Mu-Jeng,Nielsen, Robert J.,Goddard III, William A.
, p. 1322 - 1325,4 (2020/08/31)
Despite the growing importance of fluorinated organic compounds in drug development, there are no direct protocols for the fluorination of aliphatic C-H bonds using conveniently handled fluoride salts. We have discovered that a manganese porphyrin complex catalyzes alkyl fluorination by fluoride ion under mild conditions in conjunction with stoichiometric oxidation by iodosylbenzene. Simple alkanes, terpenoids, and even steroids were selectively fluorinated at otherwise inaccessible sites in 50 to 60% yield. Decalin was fluorinated predominantly at the C2 and C3 methylene positions. Bornyl acetate was converted to exo-5-fluoro-bornyl acetate, and 5a-androstan-17-one was fluorinated selectively in the A ring. Mechanistic analysis suggests that the regioselectivity for C-H bond cleavage is directed by an oxomanganese(V) catalytic intermediate followed by F delivery via an unusual manganese(IV) fluoride that has been isolated and structurally characterized.
Method for producing organic compounds by substituting halogen atoms
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Page 15; 21, (2008/06/13)
The invention pertains to a method in which a halogen atom of an organic compound is replaced with a group derived from a nucleophilic agent, at high yield and high efficiency, by the following method which includes a step of reacting the nucleophilic agent with an organic material having a halogen atom bonded to a carbon atom having four σ bonds, more specifically: a method for producing an organic compound having Q, the method including a step of reacting a compound represented by general formula (2) with an organic starting material having at least one halogen atom bonded to a carbon atom having four σ bonds so as to replace the halogen atom in the organic starting material with Q:MQa (wherein M represents an alkali metal atom, an alkali earth metal atom, or a rare earth metal atom; Q represents a moiety of an inorganic acid or an active hydrogen compound derived by eliminating a proton, wherein Q is a halogen atom different from the halogen atom in the organic starting material having the halogen atom bonded to the carbon atom having the four σ bonds; and a represents an integer of 1 to 3) in the presence of a compound represented by general formula (1) (wherein Z- represents an anion derived by eliminating a proton from an inorganic acid or an active hydrogen compound; R2 is the same or different; R2 each independently represent a C1-C10 hydrocarbon group or two R2 on the same nitrogen atom may be bonded with each other to form a ring with the nitrogen atom).
Stable dialkyl ether/poly(hydrogen fluoride) complexes: Dimethyl ether/poly(hydrogen fluoride), a new, convenient, and effective fluorinating agent
Bucsi, Imre,Toeroek, Bela,Marco, Alfonso Iza,Rasul, Golam,Prakash, G. K. Surya,Olah, George A.
, p. 7728 - 7736 (2007/10/03)
The preparation, 1H, 13C, and 19F NMR structural characterization as well as with DFT-based theoretical calculations of stable dialkyl ether/poly(hydrogen fluoride) complexes are reported. Dimethyl ether/poly(hydrogen fluoride) (DMEPHF), are stable complexes of particular interest and use. The DFT calculations, that are in agreement with NMR data, suggest a cyclic poly(hydrogen fluoride) bridged structure for DMEPHF. The complex, DME-5 HF was found to be a convenient and effective new fluorinating agent with the ease. of workup and applied to several fluorination reactions, such as the hydrofluorination and bromofluorination of alkenes, and fluorination of alcohols giving good to excellent yield with high selectivity. Homologous dialkyl ether/poly(hydrogen fluoride) (R2O/[HF]n R = Et, nPr) systems are also stable and suitable for fluorination reactions.
