R. E. Banks

Selectfluor™ reagent F-TEDA-BF4 in action: tamed fluorine at your service

Abstract This paper concerns the discovery, properties and applications in organic synthesis of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo [2.2.2]octane bis(tetrafluoroborate) (so-called F-TEDA-BF4), one of the best general-purpose user-friendly site-selective electrophilic fluorinating agents to have emerged from a vigorous search worldwide since 1980 for more generally acceptable (non-gaseous, less aggressive, non-explosive, less toxic, relatively inexpensive) reagents than perchloryl fluoride, O-F compounds like trifluoromethyl hypofluorite or caesium fluoroxysulfate, xenon difluoride or fluorine itself. The information presented is based on literature available prior to January 1997.

Electrophilic fluorination with N-fluoroquinuclidinium fluoride

Abstract N -Fluoroquinuclidinium fluoride (NFQNF), obtainable in ca . 90% yield by direct low-temperature liquid-phase fluorination of quinuclidine, has been used to deliver ‘positive’ fluorine to carbanionic sites in a number of organic substrates.

Environmental aspects of fluorinated materials. Part 2. ‘In-kind’ replacements for Halon fire extinguishants; some recent candidates

Abstract Environmental and in-use characteristics of three potential replacements for brominated fire extinguishants (Halons) are discussed, namely NAF SIII TM , FE-13 TM and FM-200 TM . Background information relating to the Montreal Protocol on Substances that Deplete the Ozone Layer, the assessment of environmental acceptability of CFC and Halon replacements, tropospheric decomposition mechanisms and fluorocarbon nomenclature is included.

N-halogeno compounds. Part 12 [1]. Site-specific fluorination of carbanions with perfluoro-N-fluoropiperidine [2]

Abstract Perfluoro-N-fluoropiperidine (1) acts as a site-selective electrophilic fluorinating agent towards carbanionic substrates [Me2CNaNO2 → Me2 CFNO2; PhMgBr → PhF; PhCNa(CO2Et)2 → PhCF(CO2Et)2; EtCNa(CO2Et)2 → EtCF(CO2Et)2; CH 2 (CH 2 ) 2 COC NaCO2Et → CH 2 (CH 2 ) 2 COC FCO2Et], but in doing so is converted to perfluoro-1- azacyclohexene (2). Unfortunately, this imidoyl fluoride (2) is highly electrophilic and competes with the NF compound (1) for carbanionic species, as exemplified by the formation of the 2-substituted octafluoro-1-azacyclohexenes CF 2 (CF 2 ) 3 NC R, where R = Ph, CEt(CO2Et)2, and C(CO 2 Et)CO(CH 2 ) 2 C H2 in the respective cases of the last three sodio derivatives listed above.

N-halogeno compounds. Part 11. Perfluoro-[N-fluoro-N-(4-pyridyl)-methanesulphonamide], a powerful new electrophilic fluorinating agent

Abstract Perfluoro-[ N -fluoro- N -(4-pyridyl)methanesulphonamide] (III), synthesised via direct fluorination of the sodio derivative of perfluoro-[ N -(4-pyridyl)methanesulphonamide] (I), readily converts diethyl sodio(phenyl)malonate and anisole to diethyl fluoro(phenyl)malonate and ortho - plus para -fluoroanisole respectively at ambient temperature; at 60 °C it quickly converts benzene to fluorobenzene. The sodio-precursor (I) of the N-F compound (III) is easily made from pentafluoropyridine and trifluoromethanesulphonamide.

N-Halogeno compounds. Part 13. N-Fluoroquinuclidinium salts — synthesis and use as electrophilic fluorinating agents

Abstract A convenient one-pot method has been developed for the preparation of the easily handledelectrophilic fluorinating agent N-fluoroquinuclidinium triflate from quinuclidine, lithiumtrifiate and fluorine. The corresponding trifluoroacetate, heptafluoro-n-butyrate and tetrafluoroboratesalts were procured in a two-step fashion by adding the appropriatesodium salts to acetonitrile solutions of N-fluoroquinuclidinium fluoride. Site-specificfluorination of phenylmagnesium bromide (to PhF), diethyl sodio(phenyl)malonate [toPhCF(CO2Et)2], 2-nitropropan-2-yl-lithium [to Me2CFNO2], 1-morpholinocyclohexene [to CH 2 (CH 2 ) 3 CHFC O], phenol (to 2- and 4-FC6H4OH+1,4-F2C6H3OH) and sodium benzenesulphinate(to PhSO2F) was achieved using these new N-fluoroquinuclidinium salts.

N-halogeno compounds. Part 9. N-Fluoroquinuclidinium fluoride—a new electrophilic fluorinating agent

N-Fluoroquinuclidinium fluoride, prepared in high yield by treatment of a cold, dilute solution of quinuclidine in trichlorofluoromethane with fluorine at low pressure in a specially designed, virtually all glass vacuum system, acts as a site-selective electrophilic fluorinating agent towards carbanionic substrates [PhCNa(CO2Et)2→ PhCF(CO2Et)2; Me2CLiNO2→ Me2CFNO2; RMgX → RF (R = Ph, X = Br; R = c-C6H11, X = Cl); [graphic omitted]H2→ [graphic omitted]HF; PhSiCl3/F–(in situ)→ PhF].

Fluorocarbon derivatives of nitrogen. Part I. Some reactions of perfluoro-1-azacyclohexene

Abstract Controlled displacement of fluorine from perfluoro-1-azacyclo-hexene (I) by the nucleophilic reagents Me2NH, Et2NH, CH 2 CH 2 O(CH 2 ) 2 N H, C6Cl5ONa, and (CF3)2NONa provides the derivatives (II) - (IV), respectively. The last of these can also be obtained by treatment of the parent compound (I) with mercuryII bistrifluoromethylnitroxide.

Fluorocarbon derivatives of nitrogen. Part 18 [1]. Synthesis of fluorinated indolizines through reactions of pyridinium ethoxycarbonylmethylide or pyridinium phenacylide with perfluoropropene, perfluorobut-2-yne and 3,3,3-trifluoropropyne

3-Ethoxycarbonyl-2-fluoro-1-trifluoromethylindolizine (6), 3-ethoxycarbonyl-1,2-(bistrifluoromethyl)indolizine (8), 3-ethoxycarbonyl-1-trifluoromethylindolizine (10) and 3-ethoxycarbonyl-2-perfluoroheptylimidazo[1,2-a]pyridine (12) have been obtained via trapping of pyridinium ethoxycarbonylmethylide with perfluoropropene, perfluorobut-2-yne, 3,3,3-trifluoropropyne and perfluorooctanenitrile respectively. Similarly, 2-fluoro-1-trifluoromethyl-3-phenacylindolizine (7), 1,2-bis(trifluoromethyl)-3-phenacylindolizine (9),and 3-phenacyl-1-trifluoromethylindolizine (11), have been obtained via reaction of pyridinium phenacylide with perfluoropropene, perfluorobut-2-yne, and 3,3,3-trifluoropropyne respectively. Alkaline hydrolysis of (8) gave 1,2-bis(trifluoromethyl)indolizine-3-carboxylic acid (16), which was decarboxylated thermally to 1,2-bis(trifluoromethyl)- indolizine (15).

Studies in azide chemistry. Part 13 [1]. Intermolecular insertion of azide-derived polyfluorinated aryl- and heteroaryl-nitrenes into ring CH bonds of 1,3, 5-trimethyl- and 1,3,5-trimethoxy-benzene

Abstract Thermolysis of perfluoroazidobenzene, perfluoro-4- azidotoluene, perfluoro-4-azidopyridine, 4-azido-3- chlorotrifluoropyridine, and 4-azido-3, 5-dichlorodifluoropyridine (ArFN3) in the presence of a large excess ( ca . 10 molar) of 1,3,5-trimethyl- or 1,3,5-trimethoxy-benzene (ArH) gave the diarylamines expected from nitrene ‘insertions’ at nuclear CH bonds (ArFN3 + ArH→ArFNHAr + N2); product yields in the cases of the perfluorinated azides are the highest ever recorded for this type of reaction. By contrast, no recognisable products were obtained when either perfluoro-(2-azido-4-isopropylpyridine) or 2-azido- 4-chlorotrifluoropyridine were decomposed thermally in 1,3,5-trimethylbenzene.