Dimsylsodium/DMSO

The most convenient method for the preparation of sodium acetylide appears to be by reaction of acetylene with sodium methylsulfinyl carbanion (dimsylsodium). The anion is readily generated by treatment of DMSO with sodium hydride, and the direct introduction of acetylene leads to the reagent. As above, the acetylide may then be employed in the ethynylation reaction. 

Permethyiation of carbohydrates. One widely used method for this reaction employs dimsylsodium in DMSO and methyl iodide. The. purity of the permethylated products is significantly improved if dimsylpotassium is used as the base.2... 

Heating of compound 1 with dimsylsodium in DMSO at 90°C for 21 hours gives a 71% yield of the epimeric ene-diesters 2. 

OL,fi-Unsaturatedsulfides. The reaction of aromatic aldehydes and DMSO with metallic sodium leads to 2-arylethenyl methyl sulfides with the (E)-ponfiguration. Presumably the actual reagent is dimsylsodium the final product is then formed by reduction of an intermediate sulfoxide by sodium. o... 

Preparation of ethers. Treatment of secondary and tertiary alcohols with dimsylsodium in DMSO followed by alkylation with a dialkyl sulfate gives ethers in 60-90% yield. The presence of ester and tertiary amino groups and of double bonds docs not interfere with the reaction. However, alkylation of a- or j8-hydroxyketones was not successful by this procedure. 

Tschugaeff reaction (3, 123). Meurling et al. have prepared xanihates in good yield by treating alcohols with an equivalent amount of dimsylsodium in DMSO followed by carbon disulfide and an alkylating agent. The decomposition temperature of the xanthates is lowered when pyrolysis is carried oul in DMSO. 

The Wharton fragmentation was used as a key step in an approach toward the total synthesis of xenicanes by H. Pfander et al. ° Two optically active substituted frans-cyclononenes were synthesized starting from (-)-Hajos-Parrish ketone. First, the bicyclic 1,3-diol was protected regioselectively on the less sterically hindered hydroxyl group with p-toluenesulfonyl chloride in quantitative yield. Next, the monosulfonate ester was exposed to dimsylsodium in DMSO, which is a strong base, to initiate the desired heterolytic fragmentation. 

Dimsylsodium (22) is an important reagent and it can be used for carbon-carbon bond formation (see Chapter 10, p. 187). DMSO may also be used in the Moffatt oxidation (see Chapter 5, p. 66) and by alkylation it can be converted into the corresponding dimethylsulfoxonium ylide which is valuable in organic synthesis (see Chapter 10, p. 187).4... 

Dimethyl sulfoxide (DMSO) (23) can be used in carbon-carbon bond formation it is a weak acid and with strong bases yields dimsylsodium (24) (Scheme 10). 

The phenomenon can also play a role in reactions where a base and a solvent able to produce a base, are brought together. For example if we consider a base in DMSO and if this base is able to generate a small quantity of dimsylsodium, which is the active species the base, dimsylsodium or the complex base base-dimsylsodium ... 

A Czech group found that dimsylsodium or dimsyllithium (by heating LiH with DMSO in THF under argon at 70-75°) reacts with 1-alkynes in DMSO or DMSO-THF to give alkali acetylides in practically quantitative yield. 

Methylatiott. Hakomori reported that glycosides of polysaccharides can bt rapidly permethylated by treatment with dimsylsodium in DMSO followed by reaction with methyl iodide ... 

Use of dimsylsodium in DMSO for formation of phosphonium ylides is particularly advantageous for the synthesis of volatile hydrocarbons because the high-boiling solvent facilitates isolation of lower-boiling products.118 Japanese workers1111 studied the methylation of aromatic hydrocarbons with dimsylsodium. Naphthalene was not sufficiently reactive, but phenanthrene gave 9-methylphenanthrene in 86%... 

Prepared in solution by treatment of ethyltriphenylphosphonium bromide (Aldrich) with base (usually /i-butyllithium).1 It has also been prepared in high yield by use of dimsylsodium as base and DMSO as solvent.2... 

Stevens rearrangement. Rearrangement of the N-methyltetrahydroprotober-berinium iodide (1) to the 1-spiroisoquinoline (2) has been effected with dimsylsodium in DMSO in 80% yield... 

Dimethyl sulfoxide reacts at temperatures in the range of 80 °C with sodium hydride to give a solution of dimsylsodium , NaCH2SOCH3 [1]. For most derivatization reactions this solution is not very attractive, since the work-up involves separation of the desired product (in many cases having a good water-solubility) from large amounts of DMSO. 

The reaction of cw-(8-arylmethyl)canadinium salts (cw-76 or 77) with dimsylsodium in DMSO afforded the 8-arylmethylcanadine 78 and 79 derivative stereoselectively with a ci5-configuration between H-14 and the substituent at C-8. ... 

A variety of bases have been used to convert sulphonium salts into ylides. In the case of an unstable ylide such as (1), irreversible generation of the ylide using dimsylsodium in DME resulted in considerable ylide decomposition, whereas the use of a weaker base system, powdered KOH in DMSO, resulted in reversible ylide formation and the maintenance of a lower concentration of ylide." Shono et al. now have published full details of the electrochemical conversion of sulphonium salts into ylides. From the corresponding sulphonium salts in aqueous solution at -1.6 to -2.1 V they were able to generate dimethylsulphonium-2-nitrofluorenylide, -benzylide, and -methylide. The former ylide was isolated while the latter two were trapped by reaction with aldehydes, ketones, and diethyl maleate in yields up to 30%. However, they were accompanied by products probably originating from radicals. 

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