Nitrosobenzene ligands

The main evidence adduced for the latter is the formation of nitrosobenzene on decomposition of the ligand. However, the common form on the left appears to be involved almost uniformly in the complexes which the ligand forms with a large variety of metals. 

Yamamoto et al. reported the asymmetric (9-nitrosoaldol reaction using silyl enol ethers in the presence of the silver catalyst.32 In order to achieve this reaction, they developed a novel combination of silver and a chiral phosphite derived from BINOL. The disilanyl enol ether was used to ensure high yield and enantioselectivity. The reaction was conducted with disilanyl enol ether and nitrosobenzene in the presence of AgBF4 and the chiral phosphite ligand in THF to produce the O adduct with high regio- and enantioselectivity (Table 9.14). In addition, a chiral silyl enol ether could be used as a substrate. The reaction was conducted with chiral silyl enol... 

On a small scale, photolysis of [Fe(CN)g] in aqueous solutions affords some [Fe(CN)5H20] . When the reaction is carried out in the presence of nitrosobenzene the loss of cyanide is accelerated resulting in the formation of the violet PhNO complex. The rate of this process is also enhanced by the presence of certain metal ions, for example Hg or Pb ". Larger scale preparations usually involve reductive removal of NO from the nitroprusside ion in the absence of potential donor ligands other than water. Thus the reaction of [Fe(C N)5NO] with hydroxyl-amine in the presence of sodium carbonate yields a yellow deliquescent powder formulated as Na3[Fe(CN)jH20]. The violet PhNO complex [Fe(C 5PhNO] , which has = 528 nm in aqueous solution, is formed when this salt reacts with nitrosobenzene. In common with many other [Fe(CN)5L] ions, reaction with an excess of cyanide yields [Fe(CN)5] . 

Metallacyclic complexes 116 and 117 have been obtained starting from nitro- and nitrosobenzene " and an intermediate of the type 118 was detected. Novel olefin palladium(ii) complexes 119 containing poly(pyrazol-l-yl)borate and -methane ligands were obtained. ... 

Scheme 5.129 Enantioselective silver-catalyzed reaction of silicon enolates 521 with nitrosobenzene 515 to a-aminooxy ketones 519, mediated by ligand 522. Reagent control in the reaction of enantiomeric silicon enolates 523.

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