Silver fluoroborate

Anhydrous silver fluoroborate [1404-20-2] is made by the addition of BP gas to a suspension of AgP ia ethylbenzene (90). An AgBP CgH Q complex is precipitated with pentane and the complex is washed with pentane to give anhydrous AgBP. ... 

The use of silver fluoroborate as a catalyst or reagent often depends on the precipitation of a silver haUde. Thus the silver ion abstracts a CU from a rhodium chloride complex, ((CgH )2As)2(CO)RhCl, yielding the cationic rhodium fluoroborate [30935-54-7] hydrogenation catalyst (99). The complexing tendency of olefins for AgBF has led to the development of chemisorption methods for ethylene separation (100,101). Copper(I) fluoroborate [14708-11-3] also forms complexes with olefins hydrocarbon separations are effected by similar means (102). 

An excess of l-chloro-3-iodopropane must be employed to compete effectively with the diphenyl sulfide for complexation with silver fluoroborate. 

Partial structures (lacking ring D ) of the bisindole alkaloids have been prepared by reaction of a substituted chloroimine with vindoline (21) under conditions that promote ionization to yield the coupled products as a mixture of diastereomers (59). Reaction of 27 with silver fluoroborate followed by addition of 21 gives 29 as a mixture of diastereomers in 49% yield. Treatment of this mixture with potassium borohydride under acid... 

S-Alkylation of 6-aroyl-277-thiopyrans with alkyl iodides in the presence of either silver fluoroborate or dialkoxycar-benium fluoroborates in CH2C12 proceeds smoothly to afford the 1-alkylthiopyranium fluoroborates (Equation 108). Methyl trifluoromethanesulfonate proved more efficient for the S-methylation of 6-cyano- and 6-methoxycarbonyl-2/7-thiopyrans C1990TL115, 2001J(P1)2269>. 

Another useful salt is silver fluoroborate, which has to be handled in a dry box. It was mostly used to substitute two geminal iodines with fluorine atoms83 and to prepare the first monofluorododecahedrane from the corresponding bromo derivative (equation 43)84. 

Further investigations have been carried out into the direct preparation of 5 -nor-alkaloids from parent alkaloids of the vinblastine group.141 The 7 -chloro-indolenines (328) and (329) derived from anhydrovinblastine and leurosine fragment in the presence of silver fluoroborate to give, after re-cyclization, the 5 -nor-bases (330) and (331). In the formation of (328) and (329), some chlorination also occurs at position 12, and this can, under appropriate conditions, form the major reaction. Products similar to (330) and (331) were also obtained from the analogous reactions with anhydrovincristine and leuroformine. 

Cycloaddition reactions of benzyne with cyclic olejms, Benzyne reacts with cyclo-hexadiene to give, as the main products, hydrocarbons (l)-(4). The first (I) arises by 2 + 4 cycloaddition, (2) and (3) arise by ene cycloadditions, and (4) is a result of 2 + 2 cycloaddition. Addition of catalytic amounts of silver fluoroborate exerts a marked effect in this case (1) becomes almost the exclusive product. Silver ton, however. 

Reaerangements of lricycldi3.2Mj0i ]h anes. Treatment of (1) with small amounts of silver fluoroborate leads to a rapid reaction with formation of the isomeric hydrocarbon (2). Similarly, (3) is converted into (4). 

Rearrangements of strained a-bonds sec Silver fluoroborate, 3, 250). Paquette et at have now examined the Ag "-catalyzed rearrangement of the less strained seco-cubanc derivatives. Treatment of the endo,endo-silver perchlorate resulted in quantitative and stereospecific conversion to the endo endo-letracyclo[3.3.0.0. 0 ]octane derivative (2). In like manner, the endo,exo-isomer (3)... 

Treatment of geranyl acetate with bromine and silver fluoroborate in nitromethane yields (78) as a model for bromonium-ion induced biosynthesis dehydration yields two alkenes (79). °... 

Electrochemically, oxidation of 38 occurs reversibly at 0.03 V (THF, SCE) and chemical oxidation with silver fluoroborate gives the corresponding orange air-sensitive 19 VE nickelocenium cation 39 (Eq. 29) [32] ... 

Oxidation of sulfides Sulfides are oxidized by the reagent to an adduct (1), which on reaction with an alcohol followed by addition of silver fluoroborate forms an alkoxy-sulfonium fluoroborate (2) in 30-40% yield. 

Silicon tetrachloride, 424-425 Silver, 164 Silver acetate, 436 Silver carbonate, 67,425 Silver carbonate-Celite, 425-426 Silver p-chlotobenzoate, 79 Silver diethyl phosphate, 428 Silver fluoroborate, 78, 81, 82, 95, 211, 428-429... 

Chromatography.2 Reverse phase chromatography on glass fibre paper using silver fluoroborate solutions as eluants has proved useful for separation of sesquiterpenes, even of mixtures that appear homogeneous on alumina and by gas-liquid chromatography. Silver nitrate is too insoluble to be used. 

Salcomine, 360 Salicylaldehyde, 96, 217, 457 Sandmeyer reaction, 87 o-Santalene, 291 Schiff bases, 66, 249 Selenium dioxide, 93, 360-362 Selenium dioxide-Hydrogen peroxide, 362 Semicarbazide, 98 Semicarbazones, 65 Sensitizers, 285-286 L-Serine, 143 Serini reaction, 459, 460 Silica gels, 453 Silver acetate, 233, 362-363 Silver benzoate, 103 Silver carbonate, 363 Silver chlorate, 363-364 Silver cyanate, 224 Silver fluoride, 364-365 Silver fluoroborate, 365-366 Silver nitrate, 224, 240, 363, 366-368, 369, 371... 

Silver fluoroborate, AgBF4 [I, 1007, before Silver iododibenzoate]. Mol. wt. 194.70. Preparation.1 Silver oxide (1.0 g.) is dissolved in 45% fluoroboric acid (7.2 g.). Synthesis of a tropone.1 The natural tropone nezukone (4) has been synthesized by addition of dichlorocarbene (CHClj,-potassium r-butoxide) to l-isopropyl-4-methoxycyclohexadiene-1,4 (2), obtained by Birch reduction of the anisole (1). The resulting adduct (3) was treated with silver fluoroborate to give the tropone (4) in... 

Silver fluoroborate (silver tetrafluoroborate), 1,1015-1018 2, 365-366. Additional suppliers Alfa Inorganics, Research Organic/Inorganic Chem. Corp. 

---