Categories: C-F Bond Formation >
Synthesis of allyl fluorides
The solid, air-stable peptide coupling reagent TFFH (tetramethylfluoroformamidinium hexafluorophosphate) activates various alcohols towards deoxofluorination under mild conditions, that are even compatible with carbonyl functional groups.
G. Bellavance, P. Dubé, B. Nguyen, Synlett, 2012, 23, 569-572.
A rapid allylic fluorination method of trichloroacetimidates with Et3N·3HF as reagent in conjunction with an iridium catalyst can be conducted at room temperature under ambient air and provides branched allylic fluorides with complete regioselectivity in high yields. The reaction shows considerable functional group tolerance. The use of [18F]KF·Kryptofix allowed 18F- incorporation in 10 min.
J. J. Topczewski, T. J. Tewson, H. M. Nguyen, J. Am. Chem. Soc., 2011, 133, 19318-19321.
A silver-catalyzed vinylogous fluorination of vinyl diazoacetates generates γ-fluoro-α,β-unsaturated carbonyls. Fluorination of farnesol and steroid derivatives was achieved.
C. Qin, H. M. L. Davies, Org. Lett., 2013, 15, 6152-6154.
In an enantioselective fluorination of allylic alcohols under chiral anion phase-transfer conditions, an in situ generation of a directing group proved crucial for achieving effective enantiocontrol. In the presence of such a directing group, a range of acyclic substrates underwent fluorination to afford highly enantioenriched α-fluoro homoallylic alcohols.
W. Zi, Y.-M. Wang, F. D. Toste, J. Am. Chem. Soc., 2014, 136, 12864-12867.
An organocatalytic system of L-proline and salicylic acid enables a highly stereoselective synthesis of α,α-difluoro-γ,γ-disubstituted butenals. The reaction offers a wide substrate scope and excellent E stereoselectivity in most cases.
S. Arimitsu, M. Nakasone, J. Org. Chem., 2016, 81, 6707-6713.
A Pd-catalyzed gem-difluoroallylation of organoborons using 3-bromo-3,3-difluoropropene (BDFP) proceeds in high efficiency with high α/γ-substitution regioselectivity. The reaction offers low catalyst loading (0.8 to 0.01 mol %), broad substrate scope, and excellent functional group compatibility, thus providing a facile route for practical application in drug discovery and development.
Q.-Q. Min, Z. Yin, Z. Feng, W.-H. Guo, X. Zhang, J. Am. Chem. Soc., 2014, 136, 1230-1233.