123950-43-6Relevant articles and documents
N-acetylation as a means to activate polyfluoroarylamines for selective ortho-hydrodefluorination by zinc in aqueous ammonia: A concise route to polyfluorobenzo azaheterocycles
Laev, Sergey S.,Gurskaya, Larisa Yu.,Selivanova, Galina A.,Beregovaya, Irina V.,Shchegoleva, Lyudmila N.,Vasil'eva, Nadezhda V.,Shakirov, Makhmut M.,Shteingarts, Vitalij D.
, p. 306 - 316 (2007)
N-Acetylation of polyfluoroarylamines is proposed as a means to remove the amino group blocking effect of their hydrodefluorination by zinc in aqueous ammonia. With pentafluoroacetanilide, the Zn ion specific effect has been demonstrated to be responsible for ortho hydrodefluorination. This regiochemistry is accompanied by the removal of a fluorine atom from the para position, which occurs predominantly in the initial phase of the process in the absence of deliberately added zinc salt. The CuCl2 additive has been found to accelerate the reaction and to propel it to double defluorination. Quantum chemical calculations suggest a diminished electron affinity of pentafluoroaniline, which is responsible for its inertness in relation to the hydrodefluorination reaction. The pentafluoroaniline radical anion, which essentially has a nonplanar structure, is prone to easy fragmentation to give an aminotetrafluorophenyl radical. For pentafluoroacetanilide, CVA experiments and quantum chemical calculations predict that the pentafluorophenyl moiety serves as the electron receptor and that the acetamido group is twisted out of coplanarity with the benzene ring; thus, together with the electron-withdrawing effect of the acetyl group, the amino group blocking effect is suppressed. On this ground, the selective ortho hydrodefluorination of polyfluoroacetanilides is developed as an important protocol for the expeditious and general synthesis of polyfluorobenzo azaheterocycles via readily accessible polyfluoroarylamines from base polyfluoroarenes. Its applicability has been illustrated by preparing quinolines that possess a polyfluorinated benzene moiety by the Skraup synthesis utilizing crude polyfluoroacetanilide hydrodefluorination products as starting materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
A new approach to polyfluoroaromatic amines with an unsubstituted position ortho to the amino group
Laev,Evtefeev,Shteingarts
, p. 43 - 46 (2001)
N-acetyl derivatives of polyfluoroaromatic amines have been found to be highly selectively defluorinated by zinc in aqueous ammonia at the position ortho to the acetamido group thus affording a new approach to potential building blocks for the synthesis o
Hydrogen Bond Directed Photocatalytic Hydrodefluorination and Methods of Use Thereof
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Sheet 5, (2021/01/22)
Methods of synthesizing compounds comprising fluorinated aryl groups are disclosed, wherein said methods utilize hydrogen bond directed photocatalytic hydrodefluorination.
Hydrogen Bond Directed Photocatalytic Hydrodefluorination: Overcoming Electronic Control
Khaled, Mohammad B.,El Mokadem, Roukaya K.,Weaver, Jimmie D.
, p. 13092 - 13101 (2017/09/26)
The photocatalytic C-F functionalization of highly fluorinated arenes is a powerful method for accessing functionalized multifluorinated arenes. The decisive step in the determining regioselectivity in fluorine functionalization is fluoride fragmentation from the radical anion of the multifluorinated arene. To date, the availability of regioisomers has been dictated by the innate electronics of the fluorinated arene, limiting the synthetic utility of the chemistry. This study investigates the remarkable ability of a strategically located hydrogen bond to transcend the normal regioselectivity of the C-F functionalization event. A significant rate acceleration is additionally observed for hydrodefluorination of fluorines that can undergo intramolecular hydrogen bonds that form 5-8-membered cycles with moderately acidic N-H's. The hydrogen bond is expected to facilitate the fragmentation not only by bending the C-F bond of the radical anion out of planarity but also by increasing the exothermicity of the fluoride extrusion step through protonation of the naked fluoride. Finally, the synthetic utility of the method is demonstrated in an expedited synthesis of the trifluorinated α-phenyl acetic acid derivative required for the commercial synthesis of Januvia, an antidiabetic drug. This represents the first synthesis of a commercially important multifluorinated arene via a defluorination strategy and is significantly shorter than the current strategy.
Synthesis of indoles with a polyfluorinated benzene ring
Politanskaya, Larisa V.,Chuikov, Igor P.,Shteingarts, Vitalij D.
, p. 8477 - 8486 (2013/09/02)
A two-step sequence consisting of a Sonogashira coupling of polyfluorinated 2-iodoanilines with terminal alkynes, followed by a KOH promoted cyclization of the 2-alkynylanilines thus formed, has been developed as a one-pot synthesis of 2-R-indoles (R=n-Bu
