L hexafluoroantimonate

Homoallylic alcohols with a silyl group attached to the terminal alkene carbon were cyclised to oxetanes in high yields by reaction with bis(.sy z-collidine)bromine(l) hexafluoroantimonate (e.g., Equation 31) <2001TL2481>. This reaction exclusively gave the four-membered cyclic ether, with the silyl group directing formation of the electrophilic intermediate for the subsequent 4-fvo-/rrg -cyclization. When the carbon /3 to the silyl group on the double bond was unsubstituted, the reaction was diastereospecific. 

Stein, L., Removal of Xenon and Radon from Contaminated Atmospheres with Dioxygenyl Hexafluoroantimonate, O SbF, Nature 243, No. 5401, 30-32 (May 4, 1973). 

Tetrahydrobenzyl alcohol (( )3-cyclohexenene-l-methanol) and 30% aqueous hydrogen peroxide were purchased from Fluka, AG. 3-Cyclohexene-1-carboxylic acid and cis-4-cyclohexene-l,2-dicarboxylic acid were used as purchased from Lancaster Chemical Co. Methyl iodide, acetic anhydride, Oxone (potassium peroxymonosulfate), Aliquot 336 (methyl tri-n-octylammonium chloride), sodium tungstate dihydrate and N,N-dimethylaminopyridine (DMAP) were purchased from Aldrich Chemical Co. and used as received. 3,4-Epoxycyclohexylmethyl 3, 4 -epoxycyclohexane carboxylate (ERL 4221) and 4-vinylcyclohexene dioxide were used as purchased from the Union Carbide Corp. (4-n-Octyloxyphenyl)phenyliodonium hexafluoroantimonate used as a photoinitiator was prepared by a procedure described previously (4). 

Intramolecular platinum-catalyzed etherification of 1,6-diphenylhexane-l,6-diol to give corresponding oxepane (Equation 8) smoothly proceeds in the presence of platinum hexafluoroantimonate in situ prepared from PtCl2 and AgSbF6 <2005SL152>. 

Silver(I) acetate, 396 Silver hexafluoroantimonate, 467 Silver imidazolate, 467 Silver nitrite-Mercury(II) chloride, 467-468 Silver(l) oxide, 468-469 Silver(II) oxide, 469 Silver perchlorate, 469-470 Silver tetrafluoroborate, 471 Silver(I) trifluoracetate, 471 Simmons-Smith reagent, 210-211, 472, 598 Sinularene, 246 Slaframine, 114, 115 Sodium amalgam, 473-475 Sodium-Ammonia, 472 Sodium benzeneselenoate, 475 Sodium bicarbonate, 476 Sodium bis(methoxyethoxy)aluminum hydride, 93, 476-477 Sodium borate, 322 Sodium borohydride, 477-479, 499 Sodium borohydride-Cobalt(IF) chloride, 479 Sodium borohydride-Methanesulfonic acid,... 

Lewis acids, should therefore be used in carbocationic polymerizations to prevent /3-proton abstraction. Hexafluoroantimonate is probably the least basic and least nucleophilic counteranion, whereas the conjugate bases of oxy acids are more basic. Anion basicity, which correlates reciprocally with the acid strength, decreases in the order HOCIO3 = HO-S02CF3 > H0S02C1 > HI > HBr > S02(0H)2 > HC1 > H0(0)CCH3. As discussed in Section B.l, triflate, and perchlorate anions are the least basic and least nucleophilic of the oxy-acid anions. 

Dinnocenzo and Conlon have described the remarkable effect of one-electron oxidation on the rate of certain vinylcyclopropane rearrangements. Exposure of several l-p-anisyl-2-vinylcyclopropane derivatives to a catalytic amount of tris(4-bromophenyl)aminium hexafluoroantimonate in acetonitrile at room temperature was found to induce ring expansion to form cyclopentenes (equation 25) temperatures in excess of 200 °C are required for the conventional thermal rearrangement cf these systems. At this time it is uncertain whether these reactions follow concerted mechanisms, or are stepwise processes involving trimethylene cation radical intermediates. 

Chloro-l-methylpyrazinium ion with liquid ammonia reacted by addition at the 2-position to give 2-amino-3-chloro-l-methyl-1,2-dihydropyrazine (24) (609). The hexafluoroantimonate salt of perfluoropyrazine has been prepared and F n.m.r. measurements used to determine the relative order of its base strength with other perfluoroheterocycles (914). Hydrogen-deuterium exchange rates of Hj and Hg in 3-chloro(and other substituted)pyrazine l-oxide(s) have been correlated with a-constants, and the logs of the H2 exchange rates have been shown to be linearly related to the pK values (745). The pK value of 3-chloropyrazine 1-oxide is - 1.05 (745). 

At low temperatures in inert solvents (such as methylene dichloride) a controlled polymerization can be effected using various acids and alkylating agents. These initiators include boron trifluoride etherate, triethylaluminum, trityl hexachloroantimonate, triethylam-monium hexachloroantimonate, diethyloxonium hexafluoroantimonate, p-toluenesulfonic acid and diethylzinc or cadmium-l,2-diol complexes. Crystalline, high molecular weight... 

BROMINATION 2,4-Diamino-l,3-thiazole hydrotribromide. Dibromoisocyanuric acid. Hexafluoroantimonic acid. 

The cationic palladium catalysts are typically prepared by reacting (cyclooctadi-enejpaUadium methyl chloride with a stoichiometric amount of the bidentate ligand to afford the (ligand) Pd(Me)Cl adduct The adduct is then reacted with an activator such as silver hexafluoroantimonate, to afford the final cationic catalyst, (hgand) l l(Me) SbF[]. The polymerization reactions were typically run at ambient temperature in toluene to afford a viscous solution of the desired copolymer. Other activators used include tris(pentafluorophenyl)borane/triethylaluminum mixtures, Nal (C,H 5(fT j)2)4 and mefhaluminoxane. 

A systematic study of the structure of the series of l,3-dioxolan-2-ylium cations (46)-(49) as their hexafluoroantimonate salts has given the molecular dimensions listed in Table 1 and shows the structures to be essentially planar at C-2 <93CJC836>. The dimensions obtained from the x-ray structure of the 2-imino-l,3-oxathiole (50) are also presented in Table 1 <93JCS(Pl)35l>. New x-ray studies include the spiro benzodioxole compound (51) <93ACS999> and the bis-dioxolane (52), where the diffraction study was used to establish the relative configuration as being that shown <90BCJ2450>. 

A. Kikkawa, T. Takata, and T. Endo, Cationic polymerization of vinyl monomers with latent initiators. 3. l-(Para-methoxybenzyl)tetrahydrothiophenium hexafluoroantimonate as a new potent cationic initiator. Makromol. Chem. Macromol. Chem. Phys. 1991,192(3), 655-662. 

---