88288-00-0Relevant academic research and scientific papers
LEWIS ACID CATALYZED HALOGENATION OF ACTIVATED CARBON ATOMS
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Page/Page column 28, (2008/06/13)
A practical and efficient method for halogenation of activated carbon atoms using readily available /V-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.
Lewis acid catalyzed highly selective halogenation of aromatic compounds
Zhang, Yanhua,Shibatomi, Kazutaka,Yamamoto, Hisashi
, p. 2837 - 2842 (2007/10/03)
A simple and efficient procedure for the halogenation of aromatic compounds with NCS, NBS, NIS and NFSI in the presence of catalytic amount of ZrCl 4 is described. Chlorination, bromination, iodination and fluorination of various aromatic compounds are performed with high selectivity under mild reaction conditions. Georg Thieme Verlag Stuttgart.
Selective and efficient direct fluorination of polycyclic aromatic hydrocarbons using 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)
Stavber, Stojan,Zupan, Marko
, p. 1077 - 1078 (2007/10/03)
A new N-F fluorinating reagent 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Accufluor NFTh) was effectively used for selective fluorination of polycyclic aromatics. Naphthalene was site-selectively fluorinated to 1-fluoronaphthalene, phenanthrene to 9-fluorophenanthrene, and pyrene to 1-fluoropyrene. In a series of substituted naphthalenes the regioselectivity and effectiveness of fluorination depended on the position and the nature of the substituents.
A Novel Electrophilic Fluorination of Activated Aromatic Rings Using Acetyl Hypofluorite, Suitable also for Introducing (18)F into Benzene Nuclei
Lerman, Ori,Yitzhak, Tor,Hebel, David,Rozen, Shlomo
, p. 806 - 813 (2007/10/02)
Acetyl hypofluorite (1) is a new compound that serves as a novel electrophilic fluorinating agent.It is special in the sense that, while it is very reactive, it is still a milder reagent than other fluoroxy compounds such as CF3OF or CF3COOF.It is synthesized directly from elemental fluorine and is used without any isolation or purification.The hypofluorite 1 reacts efficiently and selectively with activated aromatic rings,particularly phenol and aniline derivatives after suitable protection of the hydroxyl and the amino groups.The net result of the reaction is partly according to classical aromatic electrophilic substitution.Unlike such a substitution, however, the electrophilic fluorine atom of 1 substitutes mainly an ortho hydrogen and only occasionally small amounts of p-fluoro derivatives are found.Evidence supports the mechanism for this aromatic fluorination as being mainly an addition-elimination one.In many cases the electrophilic aromatic fluorinations can replace the classical 60-year-old Balz-Schiemann method, which until today is probably the most used procedure.Since aromatic fluorination with 1 is a very fast reaction and since 1 is produced directly from elemental fluorine, this is probably one of the best ways for introduction of the short-living radioisotope (18)F into activated aromatic rings.This will greatly encourage the synthesis of compounds suitable for use in the rapidly developing field of positron emitting transaxial tomography, which in itself depends on the efficient and easy supply of compounds possessing positron emitting isotopes.
