Hydrogen Bond Directed Photocatalytic Hydrodefluorination: Overcoming Electronic Control
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.
Khaled, Mohammad B.,El Mokadem, Roukaya K.,Weaver, Jimmie D.
p. 13092 - 13101
(2017/09/26)
Photocatalytic hydrodefluorination: Facile access to partially fluorinated aromatics
Polyfluorinated aromatics are essential to materials science as well as the pharmaceutical and agrochemical industries and yet are often difficult to access. This Communication describes a photocatalytic hydrodefluorination approach which begins with easily accessible perfluoroarenes and selectively reduces the C-F bonds. The method allows facile access to a number of partially fluorinated arenes and takes place with unprecedented catalytic activity using a safe and inexpensive amine as the reductant.
Senaweera, Sameera M.,Singh, Anuradha,Weaver, Jimmie D.
p. 3002 - 3005
(2014/03/21)
Direct Perfluoroalkylation Including Trifluoromethylation of Aromatic with Perfluoro Carboxylic Acids Mediated by Xenon Difluoride
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Tanabe, Yoo,Matsuo, Noritada,Ohno, Nobuo
p. 4582 - 4585
(2007/10/02)
A benzoylurea derivative and its production and use
A benzoylurea derivative represented by the formula, wherein R1 is a hydrogen atom or a fluorine atom, R2 is a trifluoromethyl group, a pentafluoroethyl group or a heptafluoropropyl group, and R3 is a hydrogen atom, a fluo
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(2008/06/13)
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