Trifluoromethanesulphonic acid (CF3SO3H), also known as triflic acid, is an important reagent and catalyst in modern synthetic chemistry. Interesting applications of triflic acid, triflic anhydride and simple salts or esters have been reviewed in literature to highlight the importance of this family of reagents in the development of novel fine chemicals and pharmaceutical synthesis1,2.
Methods for introducing the CF3 moiety into molecules are of considerable synthetic and commercial importance. The strong electron-withdrawing properties of the CF3- and –SO2- groups suggest that CF3SO2- anion, known as the triflate group, is an excellent leaving group used in certain organic reactions such as nucleophilic substitution, Suzuki couplings and Heck reactions3.
Preparative methods have evolved that utilise substituted aryl compounds as organic electrophiles for C-C bond formation via cross coupling promoted by group 10 transition metals4. Since alkyl triflates are extremely reactive in SN2 reactions, they must be stored in conditions free of nucleophiles, i.e. water. The anion owes its stability to resonance stabilization which causes the negative charge to be spread over the three oxygen atoms and the sulfur atom.
New applications continue to be made to both industrial and academic laboratories, along with already established use of triflates as Lewis acids or as counterion for organometallic complexes. The extensive chemistry of triflates is possible due to their stability compared to more traditional catalysts unstable in water, such as aluminium chloride5,6.
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References
1. A.Senning, Chem Rev., 1965, 65, 385.
2. R.D.Howells and J.D. McCown, Chem.Rev., 1977, 77, 69.
3. S.L.Taylor and J.C. Martin, J.Org.Chem., 1987, 52(19), 4147.
4. G.P. Roth and C.E. Fuller, J.Org.Chem., 1991, 56, 3494.
5. G.A.Lawrence, Chem. Rev., 1986, 86, 17.
6. P.E.Rakita, Chemistry Today, 2004(March/April), 48.
