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DOI: 10.1055/s-0031-1290085
Bis(trifluoromethanesulfonyl)imide
Publication History
Publication Date:
28 November 2011 (online)
Biographical Sketches
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Introduction
Bis(trifluoromethanesulfonyl)imide (1), or triflimide, is a commercially available Brønsted acid that has been applied to a broad range of organic transformations. [¹] In addition to being an exceptionally potent Brønsted acid, the corresponding conjugate base is more commonly employed as a weakly coordinating counterion with a variety of metal and organic catalyst systems. [²] Experimental evidence indicates that triflimide is a weaker Brønsted acid in solution than the closely related triflic acid, [³] however, the lower charge density and greater steric encumbrance results in a less coordinating anion. Consequently, triflimide-based Lewis acids generally show higher activity than their corresponding triflate counterparts. [4]
Preparation
Triflimide was first prepared by stepwise addition of trifluoromethanesulfonyl fluoride to anhydrous ammonia. [³] It has also been prepared by the reaction of trifluoromethanesulfonyl fluoride with lithium nitride followed by vacuum distillation from concentrated sulfuric acid. [5] Lewis acids are commonly prepared by treating metal halides, carbonates, hydroxides, or oxides with aqueous triflimide. [6] Silver triflimide can also be utilized in salt metathesis reactions under anhydrous conditions. [7]
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Scheme 1 Preparation of bis(trifluoromethanesulfonyl)imide
Abstracts
(A) Triflimide was found to be effective at promoting the [3,3]-sigmatropic rearrangement of Boc-protected N-allyl hydrazones. [8] The authors describe the newly forged C-C bond as traceless, since the functional groups utilized in the bond forming event are cleanly lost as volatile byproducts. |
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(B) Chiral proline-derived oxazaborolidines, when treated with triflimide, generate highly efficient and enantioselective Diels-Alder catalysts. [9] A short enantioselective synthesis of estrone was disclosed that relies on a novel N-methyl-oxazaborolidinium triflimide catalyzed Diels-Alder reaction as key step. |
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(C) Highly diasteroselective Mukaiyama cross-aldol reactions of aldehydes catalyzed by low loadings of triflimide have been reported. [¹0] In the presence of 2.2 equivalents of the silyl enol ether a diastereoselective cascade reaction resulting from double addition is observed. It is believed that the active catalyst is the Lewis acid Tf2NSi(TMS)3, formed in situ following protodesilylation. |
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(D) The (2+2) cycloaddition of silyl enol ethers with α,β-unsaturated esters proceeds with catalytic amounts of triflimide to produce substituted cyclobutanes. [¹¹] Reaction with alkynyl esters affords the corresponding cyclobutenes. Like the aforementioned Mukaiyama aldol chemistry, the reaction is believed to proceed by way of a silicon-based Lewis acid generated in situ. |
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(E) Direct arene borylation with highly electrophilic boronium cations constitutes an efficient means to construct useful aryl-boron bonds in a single step. [¹²] When 9-BBN is treated with triflimide and then 1,8-bis(dimethylamino)naphthalene a relatively stable boronium salt complex results. The salt was fully characterized then applied to the borylation of several nitrogen heterocycles. |
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(F) Gold triflimide salts react with propargylic alcohols in the presence of substituted pyridine N-oxides to afford α-oxo gold(III) carbene intermediates. [¹³] Intramolecular OH insertion affords functionalized oxetan-3-ones. The addition of stoichiometric amounts of triflimide prevents catalyst deactivation by the pyridine formed during oxidation. |
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(G) Historically, Friedel-Crafts acylation reactions are carried out with activated carboxylic acid derivatives and stoichiometric amounts of AlCl3. Catalytic triflimide or triflimide-based Lewis acids have shown activity in intermolecular Friedel-Crafts acylations with carboxylic acids, producing water as the only stoichiometric byproduct. [¹4] |
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- 2
Antoniotti S.Dalla V.Duñach E. Angew. Chem. Int. Ed. 2010, 49: 7860 - 3
Foropoulos J.DesMarteau D. Inorg. Chem. 1984, 23: 3720 - 4
Mathieu B.Ghosez L. Tetrahedron 2002, 58: 8219 - 5
Conte L.Gambaretto G.Caporiccio G.Alessandrini F.Passerini S. J. Fluorine Chem. 2004, 125: 243 - 6
Earle MJ,Mcauley J,Ramani A,Seddon R, andThomson JM. inventors; US Patent 6,998,497. - 7
Mézailles N.Ricard L.Gagosz F. Org. Lett. 2005, 7: 4133 - 8
Mundal DA.Avetta CT.Thomson RJ. Nature Chem. 2010, 2: 294 -
9a
Ryu D.Corey EJ. J. Am. Chem. Soc. 2003, 125: 6388 -
9b
Canales E.Corey EJ. Org. Lett. 2008, 10: 3271 -
10a
Boxer MB.Yamamoto H. J. Am. Chem. Soc. 2006, 128: 48 -
10b
Boxer MB.Yamamoto H. Nat. Protoc. 2006, 1: 2434 -
11a
Inanaga K.Takasu K.Ihara M. J. Am. Chem. Soc. 2005, 127: 3668 -
11b
Takasu K.Ishii T.Inanaga K.Ihara M. Org. Synth. 2006, 83: 193 - 12
Prokofjevs A.Kampf J.Vedejs E. Angew. Chem. Int. Ed. 2011, 50: 2098 -
13a
Ye L.He W.Zhang L. J. Am. Chem. Soc. 2010, 132: 8550 -
13b
Ye L.Cui L.Zhang G.Zhang L. J. Am. Chem. Soc. 2010, 132: 3258 - 14
Kawamura M.Cui D.Shimada S. Tetrahedron 2006, 62: 9201
References
J. Sun, Triflimide, In e-EROS Encyclopedia of Reagents for Organic Synthesis; John Wiley & Sons, 2010; http://onlinelibrary.wiley.com/o/eros/articles/rn01222/frame.html
- 2
Antoniotti S.Dalla V.Duñach E. Angew. Chem. Int. Ed. 2010, 49: 7860 - 3
Foropoulos J.DesMarteau D. Inorg. Chem. 1984, 23: 3720 - 4
Mathieu B.Ghosez L. Tetrahedron 2002, 58: 8219 - 5
Conte L.Gambaretto G.Caporiccio G.Alessandrini F.Passerini S. J. Fluorine Chem. 2004, 125: 243 - 6
Earle MJ,Mcauley J,Ramani A,Seddon R, andThomson JM. inventors; US Patent 6,998,497. - 7
Mézailles N.Ricard L.Gagosz F. Org. Lett. 2005, 7: 4133 - 8
Mundal DA.Avetta CT.Thomson RJ. Nature Chem. 2010, 2: 294 -
9a
Ryu D.Corey EJ. J. Am. Chem. Soc. 2003, 125: 6388 -
9b
Canales E.Corey EJ. Org. Lett. 2008, 10: 3271 -
10a
Boxer MB.Yamamoto H. J. Am. Chem. Soc. 2006, 128: 48 -
10b
Boxer MB.Yamamoto H. Nat. Protoc. 2006, 1: 2434 -
11a
Inanaga K.Takasu K.Ihara M. J. Am. Chem. Soc. 2005, 127: 3668 -
11b
Takasu K.Ishii T.Inanaga K.Ihara M. Org. Synth. 2006, 83: 193 - 12
Prokofjevs A.Kampf J.Vedejs E. Angew. Chem. Int. Ed. 2011, 50: 2098 -
13a
Ye L.He W.Zhang L. J. Am. Chem. Soc. 2010, 132: 8550 -
13b
Ye L.Cui L.Zhang G.Zhang L. J. Am. Chem. Soc. 2010, 132: 3258 - 14
Kawamura M.Cui D.Shimada S. Tetrahedron 2006, 62: 9201
References
J. Sun, Triflimide, In e-EROS Encyclopedia of Reagents for Organic Synthesis; John Wiley & Sons, 2010; http://onlinelibrary.wiley.com/o/eros/articles/rn01222/frame.html
![](https://www.thieme-connect.de/media/synlett/201120/v383_s1.gif)
Scheme 1 Preparation of bis(trifluoromethanesulfonyl)imide
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