Triflic anhydride

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Triflic anhydride is the chemical compound with the formula (CF₃SO₂)₂O. This compound is a particularly strong electrophile, useful for introducing the CF₃SO₂ group. Triflic anhydride is the acid anhydride of the strong acid triflic acid, CF₃SO₂OH.

It can be assayed by ¹⁹F NMR spectroscopy: −72.6 ppm vs. -77.3 for TfOH (std CFCl₃).

Preparation

The compound is prepared by dehydration of triflic acid using phosphorus pentoxide:^[1]

2CF₃SO₂OH + P₄O₁₀ → [CF₃SO₂]₂O + P₄O₈(OH)₂

Illustrative uses

In a representative application, is used to convert an imine into a NTf group.^[2]

It will convert phenols into a triflic ester, which enables cleavage of the C-O bond.^[3][4]

References

1. ^ Stang, P. J.; Dueber, T. E. "Preparation of Vinyl Trifluoromethanesulfonates: 3-Methyl-2-Buten-2-yl Triflate" Organic Syntheses, Collected Volume 6, p.757 (1988) (preparation of triflic anhydride from triflic acid).
2. ^ Baker, T. J. Tomioka, M.; Goodman, M. "Preparation and Use of N,N'-Di-BOC-N-Triflylguanidine" Organic Syntheses, Collective Volume 10, page 266
3. ^ McWilliams, J. C. Fleitz, F. J.; Zheng, N.; Armstrong, III, J. D. "Preparation of n-Butyl 4-Chlorophenyl Sulfide" Organic Syntheses, Collective Volume 10, page 147.
4. ^ Cai, D.; Payack, J. F.; Bender, D. R.; Hughes, D. L.; Verhoeven, T. R.; Reider, P. J.(R)-(+)- and (S)-(−)-2,2'-Bis(Diphenylphosphino)-1,1'-Binaphthyl (BINAP)" Organic Syntheses, Collective Volume 10, page 112