Silver I Tetrafluoroborate

Solubility sol benzene, toluene, nitromethane, diethyl ether, water. 

Form Supplied in white solid widely available. 

Analysis of Reagent Purity contents of Ag can be assayed conveniently by volumetric titration of Ag.  

Preparative Method can be prepared by reacting Silverfl) Fluoride with Boron THftuoride in nitromethane.  

Handling, Storage, and Precautions should be protected from light and moisture very hygroscopic. 

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In the case of 2,3-dihydro-l-benzothiepin 1-oxide (5), alkylation with iodomethane and silver (I) tetrafluoroborate leads to the methoxysulfonium salt 6 in 65% yield.86... 

The selective insertion of diphenylacetylene in the cyciopaiiadated sulfide complex 1 leads to the stable organometallic complex 2, which can be depalladated with silver(I) tetrafluoroborate to give a mixture of the dibenzothiepinium salt 3 and the dibenzo[Z>,z ]thiepin 4.91 Demethyla-tion of 3 to yield 4 is complete after refluxing overnight in chlorobenzene. The synthetic scope of this method for thiepin derivatives is limited due to their thermal instability, but the method is very suitable for the synthesis of 1//-2-benzothiopyrans.91... 

Acyl-3.4-benzo-2-azabicyclo[3.2.0]hepta-3,6-dienes 1, on heating at 250-280 C for a short time without solvent, rearrange to the 1-acyl-1-benzazepines 2 (Method A).23-38 In some cases, rearrangement is accompanied by minor amounts of Ar-aeyl-l-naphthylamine and, at higher temperatures, the acylnaphthylatnine can become the major product (see Section 3.2.2.6.). In the presence of silver(I) tetrafluoroborate (Method B) rearrangement takes place at lower temperatures but the yields of benzazepine are inferior as the silver(I) ion also catalyzes the reverse reaction (see Section 3.2.2.1.). 

The thermally induced electrocyclic ring opening of 2-alkyl- and 2-acyl-3.4-benzo-2-azabicyclo-[3.2.0]hepta-3,6-dienes 2 to l//-l-benzazepines 1 (see Section 3.2.1.4.1.1.) are photorever-sible.23,37 38 Also, l-acyl-1//-benzazepines 1 (R = acyl), in refluxing xylene in the presence of silver(I) tetrafluoroborate, are in thermal equilibrium with their valence isomers the 2-acyl-3,4-benzo-2-azabicyclo[3.2.Oj nepia-3,6-uienes 2 (R = acyl).23-38... 

Silver(I) tetrafluoroborate (2) is a yellowish powder which can be easily prepared from silver(I) oxide and boron trifluoride-diethyl ether complex (1). 

Like thallium(I) fluoride (see Section 18.2.), silver(I) tetrafluoroborate is used to convert chloro-formates into the corresponding fluoroformates, which are decomposed to the fluorides as described in Section 16.1.2. Phenyl fluoroformate (4) is obtained in moderate yield in this way from 3.68... 

Silver(I) tetrafluoroborate converts a-bromo-substituted ketones, e.g. 7, to the corresponding fluoro-substituted ketones, e. g. 8, under anhydrous conditions.69 Attempts to convert the a-chloro-substituted ketenes under the same conditions failed.69... 

The displacement of less activated halogen groups by silver(I) tetrafluoroborate to the corresponding fluorides is not so widespread. Although silver(I) tetrafluoroborate cannot be used to transform an aliphatic terminal dichloromethyl or trichloromethyl group to the corresponding fluoro compound, it has been known to work in many other cases (Table 13).70... 

Exchange-Fluorination by Reaction with Silver(I) Tetrafluoroborate General Procedure 70... 

The reaction of various bromocyclobutancs with silver(I) tetrafluoroborate gives partial or complete exchange of bromine for fluorine, depending on the reactant ratio. In some cases cyclopropanes and acyclic compounds have been formed.71... 

A method for the synthesis of glycosyl fluorides 11 starting from the glycosyl chlorides 10 with silver(I) tetrafluoroborate proceeds under very mild, homogeneous conditions.72,73 The ratio of isomers formed is dependent on the solvent used. The results are summarized in Table 14.72,73... 

Molar ratio of glycosyl chloride and silver(I) tetrafluoroborate was 1 1.2, unless otherwise stated. b Compounds obtained were proved to be identical with authentic samples. 

Chlorinated oxiranes can be treated with silver(I) tetrafluoroborate to yield the corresponding a-fluorocarbonyl compounds as major products and the isomeric a-chlorocarbonyl compounds as minor products.74... 

Trialkyl- or triaryl-1,l-difluoro-25-phosphorines can be prepared by treating the chloro or bromo derivatives with silver(I) tetrafluoroborate.75... 

Chlorosilanes78 and metal-bound chlorosilanes7980 and metal-bound chlorogermanes80 are converted with silver(I) tetrafluoroborate to the fluorides. 

Chloro- or bromocyclopentadienyl complexes of titanium and zirconium react with silver(I) tetrafluoroborate to form the corresponding fluoro complexes.81 Other complexes yielded the tetrafluoroborates. 

Glycosidation Allyl chloroformate, 9 Boron trifluoride etherate, 43 Silver(I) tetrafluoroborate, 273 Silver (I) trifluoromethanesulfonate, 274 Thallium zeolites, 296 Tin(II) trifluoromethanesulfonate, 301 Trichloroacetonitrile, 321 Grignard reactions and reactions of... 

Ruthenium tetroxide, 268 Silver(I) tetrafluoroborate, 273 8-Lactams Iodine, 148... 

For example, acetone sensitized photocyclization of 16 ° resulted in smooth conversion to 17 in 85% yield. Exposure of the hexacyclic compound 17 to silver(I) tetrafluoroborate in chloroform at room temperature resulted in a very slow [ 2 -I- 2 ] transposition. However after refluxing for 5-7 days with intermittent introduction of small additional quantities of silver(I) tetrafluoroborate, followed by removal of the silver salts by filtration through silica gel and recrystallization from ethanol gave a diazasnoutene derivative 18 in 80% yield, which on treatment with excess potassium hydroxide in aqueous ethylene glycol at 100°C afforded semibullvalene (l9)3 -308 in 65-70% yield. ... 

An electrophilic center in the y-position can also be generated from alkylmetal systems with a halogen or similar leaving group at the y-carbon. Thus, 3-bromopropyldicarbonyl(cyclopen-tadienyl)iron (3, X = Br R = H) upon treatment with silver(I) tetrafluoroborate gives cyclopropane (4, R = H) in 73% yield. Similar formations of cyclobutanes and cyclopentanes are less effective. 

The ring opening of unreactive gem-dichlorocyclopropanes can occasionally be improved by using silver(I) tetrafluoroborate supported on alumina as reagent without solvent (dry reaction) under microwave aetivation. " ... 

The action of tris(trimethylsilyl)phosphane on 2,4,6-triaryl-1,3,5-oxadiazinium tetrafluorobo-rates, obtained by treating acetonitrile solutions of the pentachlorostannates with silver(I) tetrafluoroborate, gives 2,4,6-triaryl-l,3,5-/l3-diazaphosphinines 6 in 5-6% yield. This is the only route to this ring system.75... 

The preparation of vinyl nitrones by catalytic cyclization of allenic oximes has been demonstrated. Oxime 75, prepared from 5,6-heptadienal, was cyclized to nitrone 76 in the presence of silver(I) tetrafluoroborate. This was trapped by, for example, styrene to give 77. Such a compound again opens up a route to 2,6-disubstituted piperidines (85TL6249). 

Silver(I) tetrafluoroborate has been used to prepare a-fluoro carbonyl compounds from chlorinated epoxides.1 25 - 127 Minor byproducts of the reaction are the corresponding a-chloro carbonyl compounds. 

Another variant of this intriguing concept was reported by Pour and co-workers using a mixture of silver(I) tetrafluoroborate and tris-2-furylphosphinegold(I) chloride in combination with methanol (11MI9390). As shown in Scheme 25, a range of acceptor-substituted propargyl vinyl ethers 75 were converted into dihydropyrans 76 in high yields. However,... 

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