Categories: C-F Bond Formation >
Synthesis of fluoroarenes
Drawbacks associated with the classic Balz-Schiemann reaction are eliminated in a series of examples by conducting fluorodediazoniation in ionic liquid solvents.
K. K. Laali, V. J. Gettwert, Journal of Fluorine Chemistry, 2001, 107, 31-34.
A palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is operationally simple and amenable to multigram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway that involves a Pd(III) intermediate.
A. R. Mazzotti, M. G. Campbell, P. Tang, J. M. Murphy, T. Ritter, J. Am. Chem. Soc., 2013, 135, 14012-14015.
Electron-rich aryl boronic acids or pinacol esters were converted in good yields and fast reactions to the corresponding aryl fluorides using readily obtainable solutions of AcOF. In reactions with aryl boronic acids containing EWG at the para position, fluorination ortho to the boronic acid is in competition with an ipso substitution. With EWG meta to the boronic acid, substitution ipso to the boron moiety takes place in good yields.
I. Vints, J. Gatenyo, S. Rozen, J. Org. Chem., 2013, 78, 11794-11795.
A new biaryl monophosphine ligand enables a room-temperature Pd-catalyzed fluorination of various activated (hetero)aryl triflates and bromides with high regioselectivity. Analysis of the solid-state structures of several Pd(II) complexes, as well as density functional theory (DFT) calculations help to explain the enhanced reactivity.
A. C. Sather, H. G. Lee, V. Y. De La Rosa, Y. Yang, P. Müller, S. L. Buchwald, J. Am. Chem. Soc., 2015, 137, 13433-13438.
Functionalized aryl- or heteroarylmagnesium reagents, prepared from the corresponding bromides or iodides using halogen-magnesium exchange or direct magnesium insertion in the presence of lithium chloride, reacted smoothly with N-fluorobenzenesulfonimide to give the corresponding aromatic fluorides in good yields.
S. Yamada, P. Knochel, Synthesis, 2010, 2490-2494.
A mild copper-mediated fluorination of aryl stannanes and aryl trifluoroborates with N-fluoro-2,4,6-trimethylpyridinium triflate (NFTPT) demonstrates broad substrate scope and functional group tolerance, and does not require the use of any noble metal additives. The reaction is proposed to proceed via an arylcopper(III) fluoride intermediate.
Y. Ye, M. S. Sanford, J. Am. Chem. Soc., 2013, 135, 4648-4651.
A mild Cu-catalyzed nucleophilic fluorination of unsymmetrical diaryliodonium salts with KF preferentially fluorinates the smaller aromatic ligand on iodine(III). The reaction exhibits a broad substrate scope and proceeds with high chemoselectivity and functional group tolerance.
N. Ichiishi, A. J. Canty, B. F. Yates, M. S. Sanford, Org. Lett., 2013, 15, 5134-5137.
PhenoFluorMix, a mixture of N,N'-1,3-bis(2,6-diisopropylphenyl)chloroimidazolium chloride and CsF, overcomes the challenges associated with hydrolysis of PhenoFluor. PhenoFluorMix does not hydrolyze, is readily available on decagram scale, and is storable in air. The reagent can be used for the deoxyfluorination of various phenols and heterocycles.
T. Fujimoto, T. Ritter, Org. Lett., 2015, 17, 544-547.
An operationally simple ipso fluorination of phenols with a new deoxyfluorination reagent can be used conveniently from miligram to multigram scale. Whereas hydrogen bonding is undesirable on conventional nucleophilic fluorination chemistry because it reduces the nucleophilicity of fluoride, hydrogen bonding appears to be crucial for this fluorination method.
P. Tang, W. Wang, T. Ritter, J. Am. Chem. Soc., 2011, 133, 11482-11484.