Silver tetrafiuoroborate

Catalysts. Silver and silver compounds are widely used in research and industry as catalysts for oxidation, reduction, and polymerization reactions. Silver nitrate has been reported as a catalyst for the preparation of propylene oxide (qv) from propylene (qv) (58), and silver acetate has been reported as being a suitable catalyst for the production of ethylene oxide (qv) from ethylene (qv) (59). The solubiUty of silver perchlorate in organic solvents makes it a possible catalyst for polymerization reactions, such as the production of butyl acrylate polymers in dimethylformamide (60) or the polymerization of methacrylamide (61). Similarly, the solubiUty of silver tetrafiuoroborate in organic solvents has enhanced its use in the synthesis of 3-pyrrolines by the cyclization of aHenic amines (62). 

Another route to the amido complexes originates from [(>j-Tp )W(CO) (PhC=CMe)(OTf)l and benzylamine and yields [(i -Tp )W(CO)(PhC=CMe) (NHCH2Ph)] (96JA6916). The latter can be protonated with tetrafluoroboric acid to give the amine derivative [(> -Tp )W(CO)(PhC=CMe)(NH2CH2Ph)](Bp4), and this process can be reversed by -butyllithium. Hydride abstraction by silver tetrafiuoroborate, molecular iodine, or PhsCPEe leads to the cationic imine derivatives [(> -Tp )W(CO)(PhC=CMe)(HN=CHPh)]". -Butyllithium deproto-nates the product and gives the neutral azavinylidene species [(> -Tp )W(CO) (PhC=CMe)(N=CHPh)]. The latter with silver tetrafiuoroborate forms the cationic nitrile species [(j -Tp )W(CO)(PhC=CMe)(N=CPh)](Bp4). 

Triphenylmethyl-4-methyl-2,8,9-trioxa-1-phosphaadamantane Tetrafluoroborate from Isomers A and B. To 1.00 g. (5.12 mmoles) of silver tetrafiuoroborate in acetone (10 ml.) was added a solution of 1.43 g. (5.12 mmoles) of triphenylmethyl chloride in acetone (15 ml.). After 5 min., the filtered solution was added to a stirred suspension of 0.90 g. (12 mmoles) of isomer A in acetone (20 ml.). After 4 hrs., a colorless precipitate formed which was filtered off and dried under vacuum at room temperature. The colorless solid (0.52 g., 30% yield), was shown to be identical with an authentic sample of l-triphenylmethyl-4-methyl-2,8,9-trioxa-l-phosphaadamantane tetrafluoroborate (16) by infrared spectroscopy. A similar procedure with isomer B gave the same product in 31% yield. 

In general, a,a-dihalocyclobutanones do not undergo the ring contraction in the presence of nucleophiles but suffer cleavage instead . It has been reported, however, that 7,7-dichlorobicyclo[3.2.0]heptan-6-one (239) affords exclusively exo-6-chlorobicyclo [11.0] hexane en io-6-carboxylic acid (R = H) and ester (R = Me) (240) in 24 and 11.5 % yield respectively, upon treatment with silver tetrafiuoroborate in boiling aqueous methanol (equation 160) . 

CycUzation. The last step in a total synthesis of ibogamine (2) involved cyclization of 1 with bis(acetonitrile)dichloropalladium(II) assisted by silver tetrafiuoroborate and triethylamine. Work-up included reduction of an intermediate palladium species with NaBH. The alkaloid was obtained in 40-45% yield. This cyclization is related to the olefin arylation of Heck, catalyzed with phenylpalladium acetate, CeHsPdOCOCHa. ... 

Treatment of dibenzothiophene with alkyl halides in the presence of silver tetrafluoroborate or triaryloxonium tetrafiuoroborate has recently been shown to yield the corresponding 5-alkyl salts of type g0 96,359 Compounds thus prepared include 5-methyl- (93%), 5-ethyl-(98%), and 5-isopropyldibenzothiophenium tetrafiuoroborate (14%). The products were thermally unstable, reverting to dibenzothiophene, although the corresponding perchlorates were more stable. 5-Methoxy-... 

Silver oxide, 527, 558, 683, 1011-1015 Silver perchlorate, 1187 N-Silver succinimide, 510 Silver sulfate, 1615 Silva tetrafiuoroborate 1015-1618 Silver p-toluenesulfonate, xe Silver to late Silver tosylate, 303,737,1618 Silva tfifluoroacetate, 495, 504,1618-1019, 1220,1227... 

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