Sulfoxide-metal exchange reactions

Likewise, the sulfoxide-metal exchange reaction of /3-acetoxy sulfoxides 164 (/3-mesyloxy sulfoxides can also be used), which are prepared from alkenyl aryl sulfoxides 163 and aromatic aldehydes, with a Grignard or alkyllithium reagent at low temperatures gives the allenes 162 in good to excellent yield (Scheme 5.24) [65],... 

H - Metal exchange or Halogen - Metal exchange or Sulfoxide - Metal exchange reaction... 

In 1993, Satoh and coworkers reported the preparation of lithium- and magnesium-aUtylidene carbenoids from 1-chlorovinyl phenyl sulfoxides by sulfoxide-metal exchange reaction at low temperature (Scheme 6). 1-Chlorovinyl phenyl sulfoxide (128) is easily synthesized from the corresponding aldehyde and chloromethyl phenyl sulfoxide in high yield. Sulfoxide 128 was treated with f-BuLi in THF at —78 °C to give the terminal alkyne 131. Obviously, the intermediate of this reaction was the alkylidene carbenoid 129. 

The male bean weevil sex attractant has been made by a new method of allene synthesis from aldehydes and alkenyl aryl sulfoxides by sulfoxide-metal exchange as the key reaction. 

The complications which result from the hydrolysis of alkali metal cyanides in aqueous media may be avoided by the use of non-aqueous solvents. The one most often employed is liquid ammonia, in which derivatives of some of the lanthanides and of titanium(III) may be obtained from the metal halides and cyanide.13 By addition of potassium as reductant, complexes of cobalt(O), nickel(O), titanium(II) and titanium(III) may be prepared and a complex of zirconium(0) has been obtained in a remarkable disproportion of zirconium(III) into zirconium(IV) and zirconium(0).14 Other solvents which have been shown to be suitable for halide-cyanide exchange reactions include ethanol, methanol, tetrahydrofuran, dimethyl sulfoxide and dimethylformamide. With their aid, species of different stoichiometry from those isolated from aqueous media can sometimes be made [Hg(CN)3], for example, is obtained as its cesium salt form CsF, KCN and Hg(CN)2 in ethanol.15... 

The synthesis of 3 was initiated by reaction of wBuLi with the protected cyclopentenone 2 generating the corresponding vinyllithium reagent by halogen-metal exchange. Subsequent condensation with (S)-(-)-menthyl para-toluenesulfinate (13) provides the enantiodefined sulfoxide substituent in 3.5 Since thermal equilibration of chiral sulfoxides at room temperature is slow, the large sulfur atom is a preferred reaction site in synthetic intermediates to introduce chirality into carbon compounds. 

Both the metallation of sulfoxides and the reaction of a-lithio sulfoxides in THF are known to be highly stereoselective. " It has been found that, on reaction with base, the diastereotopic methylene protons of benzyl methyl sulfoxide exchange at different rates, the relative ratio being... 

The salts, [PPN]n[M(CN)6] (M = Fe, n = 3 or 4 M = Ru, n = 4 M = Co, n = 3) and [PPN][Fe(CN)5(NO)], have been prepared by metathetical exchange reactions in aqueous solution between [PPN]C1 and the corresponding alkali metal salts of the cyanometallates7 Unlike alkali metal salts, the [PPN]+ salts are very soluble in chlorinated solvents and in most polar, aprotic solvents including acetonitrile, acetone, and dimethyl sulfoxide. 

Zirconium tetrachloride is instantly hydrolyzed in water to zirconium oxide dichloride octahydrate [13520-92-8]. Zirconium tetrachloride exchanges chlorine for 0x0 bonds in the reaction with hydroxylic ligands, forming alkoxides from alcohols (see Alkoxides, METAl). Zirconium tetrachloride combines with many Lewis bases such as dimethyl sulfoxide, phosphoms oxychloride and amines including ammonia, ethers, and ketones. The zirconium organometalLic compounds ate all derived from zirconium tetrachloride. 

Reactions of organomagnesium compounds with sulfoxides often result in ligand exchange [31], and may be complicated by a- or ortho metallation. However, in some cases, notably with 2-pyridyl aryl sulfoxides, reactions with arylmagnesium halides give useful yields of products from displacement of the aryl sulfoxido group [32, 33], e.g. [32]... 

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