Gold complexes metathesis

Similar observations were made with bis[alkoxy(alkylamino)carbene]gold complexes, which are prepared by ring opening of trinuclear precursors with trifluoromethanesulfonic (triflic) acid. Through anion metathesis, several crystalline forms were obtained, the structures of which were determined. The triflate salt has a chain of cations in the crystal, while the chloroform solvate of a />-benzoquinolate contains only monomeric cations. In the solvent-free crystals, dimers are present (Scheme 59).251... 

S Platinum and Gold in Metathesis In connection with the palladium-mediated metathesis, Trost has also shown that platinum complexes like (PPh3)2Pt(OAc)2 are able to catalyze this reaction [43]. Murai and coworkers expanded the scope of the reaction utilizing the versatile PtCl catalyst with a broad range of substrates (Scheme 7.24) [48]. 

A whole series of (imidazol-2-ylidene)gold(i) complexes with the 1 1 stoichiometry has been prepared from the readily available silver chloride adducts, which upon reaction with (Me2S)AuCl, followed by chloride metathesis, give the complexes shown in Scheme 60. 

Interest in the synthesis and structural characterisation of less common metalloorganophosphide systems has continued. A range of alkali metal complexes of the phosphide anion (48) has been prepared from the lithio-phosphide by simple metathesis with alkali metal alkoxides. The lithio-phosphide exists as a dimer, but crystallisation of the sodium and potassium drivatives in the presence of TMEDA results in the formation of monomeric species. The caesium triphosphenide (49), involving a phosphorus analogue of the allyl anion, has been prepared from the previously described sodium complex. Unlike the sodium and potassium complexes, which are monomeric, the caesium complex has a polymeric structure. A variety of arylphosphide complexes of magnesium, calcium, strontium and barium have been prepared and their solid state structures characterised. Cop-per(I)-, silver(I)- and gold(I)-complexes of the cyclo-(P ion have also... 

In order to optimize the reaction conditions, a series of complexes were screened (Table 2.2). The best ratios were obtained with cationic gold(I) complexes (Table 2.2, entries 1-3). [AuCl(PPh3)]/AgSbF6 gave a nearly 1 1 mixture of dihydropyran I-16a and metathesis-type product I-17a (Table 2.2, entry 1). However, a similar ratios of I-16a/I-17a = 2.3 1 were observed with phosphine gold(I) 16 and phosphite gold(I) 20 (Table 2.2, entries 2-3). No difference between the results with the cationic phosphite gold(I) 20 and the in situ form... 

In general, we observed an increase in the yield of the dihydropyran products 1-16 using IPr gold(I) complex 16 (Table 2.4, entries 4,6,8,13,16 and 18). On the other hand, using phosphite complex 20, the metathesis product 1-17 is favored (Table 2.4, entries 3, 5, 7 and 16). 

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