:Perfluorobutanesulfonyl fluoride

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Commercially available NfF is contaminated with 6-10 mol % perfluorosulfolane derived from its production. This is readily removed by vigorously stirring the commercial material with a concentrated aqueous solution of K₃PO₄ and K₂HPO₄ in a 1:1 molar ratio for 96 hours. This treatment, followed by removal of the aqueous layer and distillation from P₂O₅, gives a product that contains >99 mol % NfF with near quantitative recovery.{{Cite journal

| doi = 10.1055/s-2007-991084

| issn = 0936-5214

| volume = 2007

| issue = EFirst

| pages = 2907–2911

| last = Vogel

| first = Michael A. K.

| author2 = Christian B. W. Stark |author3=Ilya M. Lyapkalo

| title = A Straightforward Synthesis of Alkenyl Nonaflates from Carbonyl Compounds Using Nonafluorobutane-1-sulfonyl Fluoride in Combination with Phosphazene Bases

| journal = Synlett

| year = 2007

}}

As mentioned above, aryl and alkenyl nonaflates are useful as electrophiles in palladium catalyzed cross coupling reactions. Their reactivity generally mirrors that of the more commonly encountered triflate electrophiles, but nonaflates tend to be less prone to hydrolysis to ketones (in the case of alkenyl sulfonates) and phenols (in the case of aryl sulfonates). Their resistance to hydrolysis makes nonaflates superior electrophiles in Buchwald-Hartwig couplings, where this side reaction can be deleterious to yields of the desired product.

The sodium enolates of β-ketoesters react with 1.15 equivalents of NfF to give the corresponding alkenyl nonaflates in high yield. Ethyl 2-methylacetoacetate (R=R'=Me) gives the geometrically pure E isomer by this method.{{Cite journal

| doi = 10.1016/S0040-4020(98)01221-6

| issn = 0040-4020

| volume = 55

| issue = 7

| pages = 2103–2112

| last = Bellina

| first = Fabio

| author2 = Donatella Ciucci |author3=Renzo Rossi |author4=Piergiorgio Vergamini

| title = Synthesis of vinyl nonaflates derived from β-ketoesters, β-diketones or α-diketones and their palladium-catalyzed cross-coupling reactions with organozinc halides

| journal = Tetrahedron

| date = 1999-02-12

}}

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Simple aldehydes and ketones react with NfF in the presence of bases such as DBU or phosphazenes to give alkenyl nonaflates in high yields without formation of a discrete enolate. Use of the P₂ phosphazene base at -30 to -20 °C gives the less substituted alkenyl nonaflate with unsymmetrically substituted ketones. Similar reactions with triflic anhydride generally require the use of the expensive 2,6-di-tert-butylpyridine to achieve high yields.

The reaction of enolates with NfF depends strongly both on the structure of the enolate and its metal counterion. The lithium enolates of methyl ketones give mixtures of products derived from electrophilic attack on the O (expected) or C (unexpected) atoms of the enolate. This effect is particularly evident with the lithium enolate of pinacolone, which gives a 2:1 mixture favoring C-attack. More substituted lithium enolates give only products of O sulfonylation in variable yields.{{Cite journal

| doi = 10.1002/1099-0690(200203)2002:6<1015::AID-EJOC1015>3.0.CO;2-K

| issn = 1099-0690

| volume = 2002

| issue = 6

| pages = 1015–1025

| last = Lyapkalo

| first = Ilya M. |author2=Matthias Webel |author3=Hans-Ulrich Reißig

| title = An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations

| journal = European Journal of Organic Chemistry

| year = 2002

}}

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Trimethylsilyl enol ethers react with NfF in the presence of a substoichiometric fluoride source at 0 °C to ambient temperature to give alkenyl nonaflates in moderate to good yields. Dried tetra-n-butylammonium fluoride was the preferred fluoride source in one study, but CsF has been used in difficult cases with excellent results.{{Cite journal

| doi = 10.1055/s-1999-2892

| issn = 0936-5214

| volume = 1999

| issue = 10

| pages = 1654–1656

| last = Bräse

| first = Stefan

| title = Synthesis of Bis(enolnonaflates) and their 4-exo-trig-Cyclizations by Intramolecular Heck Reactions

| journal = Synlett

| year = 1999

}}

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Aryl nonaflates can be prepared straightforwardly from phenols and NfF in the presence of bases such as potassium carbonate{{Cite journal

| doi = 10.1021/jo200443u

| issn = 0022-3263

| volume = 76

| issue = 11

| pages = 4552–4563

| last = Shekhar

| first = Shashank

| author2 = Travis B. Dunn |author3=Brian J. Kotecki |author4=Donna K. Montavon |author5=Steven C. Cullen

| title = A General Method for Palladium-Catalyzed Reactions of Primary Sulfonamides with Aryl Nonaflates

| journal = J. Org. Chem.

| year = 2011

| pmid = 21510695

}} and Et₃N{{Cite journal

| doi = 10.1016/j.tet.2007.11.074

| issn = 0040-4020

| volume = 64

| issue = 7

| pages = 1218–1224

| last = Meadows

| first = Rebecca E.

| author2 = Simon Woodward

| title = Steric effects in palladium-catalysed amination of aryl triflates and nonaflates with the primary amines PhCH(R)NH2 (R=H, Me)

| journal = Tetrahedron

| date = 2008-02-11

}} in near quantitative yields. Stronger bases such as NaH and BuLi{{Cite journal

| doi = 10.1016/j.tet.2007.11.095

| issn = 0040-4020

| volume = 64

| issue = 8

| pages = 1829–1833

| last = Uemura

| first = Minoru

| author2 = Hideki Yorimitsu |author3=Koichiro Oshima

| title = Cp∗Li as a base: application to palladium-catalyzed cross-coupling reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes

| journal = Tetrahedron

| date = 2008-02-18

| hdl = 2433/88969

| hdl-access = free

}} can also be used, but they tend to give somewhat lower yields.

The reaction of NfF with alcohols highlights the lability of alkyl nonaflates – in most cases, the final product of the reaction is either an alkyl fluoride (from F⁻ attack on the intermediate alkyl nonaflate) or an olefin (from elimination of NfOH from the intermediate nonaflate). It has recently been discovered that upon reaction of NfF with alcohols to generate alkyl nonaflate, the released F⁻ can be used to activate trimethylsilyl-bound nucleophiles in situ to produce several deoxy-diversified products.{{Cite journal |last=Odoh |first=Amaechi Shedrack |last2=Keeler |first2=Courtney |last3=Kim |first3=Byoungmoo |date=2024-05-01 |title=SuFEx-Enabled Direct Deoxy-Diversification of Alcohols |url=http://dx.doi.org/10.1021/acs.orglett.4c01016 |journal=Organic Letters |volume=26 |issue=18 |pages=4013–4017 |doi=10.1021/acs.orglett.4c01016 |issn=1523-7060|url-access=subscription }}

NfF reacts with ammonium chloride in the presence of triethylamine in acetonitrile to give the triethylammonium salt of the superacidic bis-nonafluorobutanesulfonimide in 97% yield. The corresponding potassium salt is obtained by treatment of a methanolic solution of the triethylammonium salt with KOH.{{Cite journal

| doi = 10.1016/j.tet.2006.01.015

| issn = 0040-4020

| volume = 62

| issue = 13

| pages = 3137–3145

| last = Quek

| first = Ser Kiang

| author2 = Ilya M. Lyapkalo |author3=Han Vinh Huynh

| title = Synthesis and properties of N,N′-dialkylimidazolium bis(nonafluorobutane-1-sulfonyl)imides: a new subfamily of ionic liquids

| journal = Tetrahedron

| date = 2006-03-27

}} The acid is obtained by ion exchange chromatography of the triethylammonium salt with Amberlite IR-100 as the stationary phase and methanol as the eluent.{{Cite journal

| doi = 10.1002/adsc.201000126

| issn = 1615-4169

| volume = 352

| issue = 8

| pages = 1315–1337

| last = Hashmi

| first = A. Stephen K.

| author2 = Tobias Hengst |author3=Christian Lothschütz |author4=Frank Rominger

| title = New and Easily Accessible Nitrogen Acyclic Gold(I) Carbenes: Structure and Application in the Gold-Catalyzed Phenol Synthesis as well as the Hydration of Alkynes

| journal = Advanced Synthesis & Catalysis

| year = 2010

}} The actual species produced in the latter procedure is likely MeOH₂⁺ Nf₂N⁻.

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Category:Perfluorinated compounds

Category:Sulfonyl halides