AgSbF

The silver fluorocomplexes, ie, silver hexafluoroantimonate [26042-64-8], AgSbF silver hexafluorophosphate [26042-63-7], AgPF silver tetrafluoroborate [14104-20-2], AgBF and other salts such as silver trifluoromethane sulfonate [2923-28-6], CF SO Ag, and silver trifluoroacetate [2966-50-9], CF COOAg, play an important role in the synthesis of organic compounds and have gained potential industrial importance. 

These compounds perform a dual function in synthesis procedures. The introduction of a complex anion assists in the stabilization of the desired product and the generation of unique intermediates by chloride displacement, eg, silver hexafluorophosphate, AgPF, forms adducts with neutral diamagnetic organometaHics which can act as controUed sources of highly reactive cations (29). Silver hexafluoroantimonate, AgSbF, is an electrophilic... 

Bromination and chlorination of alkanes and cycloalkanes can also take place by an electrophilic mechanism if the reaction is catalyzed by AgSbFs. " Direct chlorination at a vinylic position by an electrophilic mechanism has been achieved... 

Ruthenium complexes have also been reported as active species for enan-tioselective Diels-Alder reactions. Faller et al. prepared a catalyst by treatment of (-)-[( ] -cymene)RuCl(L)]SbF6 with AgSbFe resulting in the formation of a dication by chloride abstraction [95]. The ligand was (-l-)-IndaBOx 69 (Scheme 36) and the corresponding complex allowed the condensation of methacrolein with cyclopentadiene in 95% conversion and 91% ee. As another example, Davies [96] prepared the complex [Ru(Fl20)L ( i -mes)] [SbFe]2 (with 70 as L in Scheme 36), and tested its activity in the same reaction leading to the expected product with similar activity and lower enan-tioselectivity (70%). 

Allyl-Pd(ll) complexes featuring a single NHC ligand have been explored for norbomene polymerisation. The first such disclosure appears in a patent of 2006 [39] in which complexes of the form 34 (Fig. 4.12) are activated with AgSbF and LiB(CgFj). The resulting cationic complexes catalyse the polymerisation of norbomene and polar-substituted norbomenes with very high activity. The best result... 

Allenedienes 106 were submitted to a [4+3] intramolecular cycloaddition in presence of a [AuCl(lPr)]/AgSbF catalytic system (Scheme 5.28) [28]. The cycloaddition adducts 107 and/or 108 were obtained in good yields at room temperature. In contrast, this cycloaddition reaction requires a much higher temperature (110°C) when PtCl is employed as the catalyst [29]. This fact shows that the use of [AuCl(IPr)]/AgSbF catalytic system is critical for the success of this cycloaddition. 

The hydration of C-C triple bonds represents one of the most atom economical and environmentally friendly oxidation reactions [37], Recently, Nolan and co-workers reported the cationic [Au(lPr)][SbF ] system, which was generated in situ from [AuCl(lPr)] and AgSbF. The catalyst system showed remarkable activity in the hydration of a large range of alkynes, at An loadings as low as 10 ppm (typically 50-100 ppm), under acid-free conditions (Table 10.6) [38],... 

Table 10.6 [AuCl(IPr)]/AgSbF catalysed hydration of alkynes [38] ...

To facilitate ionization of -DCC, it was premixed with AgSbFe prior Jo monomer introduction. The -dicumyl cation [(CH3)2C -CeHi(-C (CH3)2] may also form during premixing. 

Quasiliving Polymerization of Methyl Vinyl Ether. Similarly to IBVE polymerization, MVE was polymerized with premixed p-DCC/AgSbF initiating systems in CH2CI2 solvent at -70°C by slow and continuous monomer addition. Polymer yields were vL00% at every reaction time. ... 

Figure 5. Mn and N as functions of monomer input WIBve in n-heptane at —70°C. [p-DCC]0 is 0.50 mM [AgSbFs]0 is 1.1 mM. 1BVE addition rates (g/min) are 0.38 (9), 0.57 (O), 0.78 (9). The dashed lines show the data obtained in CHtCU under the same conditions.

The enantiopure BIPHEP-Pt complexes can act as chiral Lewis acids for the enantioselective Diels-Alder and carbonyl-ene reactions. The Diels-Alder products are obtained in 92-94% ee (93 7 = endo exo) and 92-94% ee (94 6 = endo exo) by (R)- and (5)-36, respectively (Scheme 8.3 la)." In the carbonyl-ene reaction catalyzed by the dication species generated from BlPHEP-PtCL 35 and AgSbFs, the (S )- and (/ )-ene products are obtained with 71% ee (99% conversion at room temperature) and 70% ee (90% conversion at room temperature) from (/ )- and (S)-35, respectively (Scheme 8.31b). 

With an eye toward increasing efficiency and eliminating the atom-uneconomical solvent waste stream involved in most organic reactions, a reusable, water-soluble catalyst, using bidentate phosphine 107 as a ligand, has been developed [36]. The catalyst is prepared by treatment of [RhCl(nbd)]2 (nbd=norbornadiene) with AgSbFs in acetone, followed by introduction of the phosphine ligand [37]. In the presence of 10 mol% catalyst in water/methanol (1 1) at a catalyst concentration of 2.0 mM, 108 reacted efficiently at 70°C to provide cycloadduct 109 after 12 h in 91% yield (GC analysis Tab. 13.8). Notably, the yield and rate compare favorably to results obtained with Wilkinson s catalyst... 

Bromination and chlorination of alkanes and cycloalkanes can also take place by an electrophilic mechanism if the reaction is catalyzed by AgSbF. "2 Direct chlorination at a vinylic position by an electrophilic mechanism has been achieved with benzenescleninyl chloride PhSe(0)Cl and AIC13 or AIBr3. n However, while some substituted alkenes give high yields of chloro substitution products, others (such as styrene) undergo addition of Cl2 to the double bond (5-26).113 Electrophilic fluorination has already been mentioned (p. 690). 

Cationic chiral Rh and Ru complexes were prepared by reaction of [(T -C5H5)RhCl2]2 and [RuCl2(T 6-mes)]2 with chiral bidentate or monodentate oxazoline ligands, respectively. Treatment of these monocationic metal complexes, with AgSbF produced dicationic complexes, which were also found to be highly effective for the enantioselective Diels-Alder reaction of methacrolein [12,13] (Eq. 8A.6). On the basis of spectroscopic and structural studies, a full catalytic cycle of a chiral Ru complex was proposed for the Diels-Alder reaction of cyclopen-tadiene with methacrolein [14]. 

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