Dimethyl sulfoxide-iodide

Isotope labeling by derivative formation with deuterated reagents is useful for the preparation of analogs such as dg-acetonides, da-acetates, da-methyl ethers, dg-methyl esters, etc. The required reagents are either commercially available or can be easily prepared. (The preparation of da-methyl iodide is described in section IX-F. Various procedures are reported in the literature for the preparation of dg-acetone, da-diazometh-ane57.i63.i73 and da-acetyl chloride. ) These reactions can be carried out under the usual conditions and they need no further discussion. A convenient procedure has been reported for the da-methylation of sterically hindered or hydrogen bonded phenolic hydroxyl functions by using da-methyl iodide and sodium hydroxide in dimethyl sulfoxide solution. This procedure should be equally applicable to the preparation of estradiol da-methyl ether derivatives. 

A mixture of methyl iodide (48 ml) and dimethyl sulfoxide (26 g) is heated under reflux for 3 days, cooled and the precipitated trimethylsulfoxonium... 

The recovered dg-dimethyl sulfoxide may be recycled to prepare additional deuteriomethyl iodide or purified for use as a reagent by gentle warming with a little solid sodium thiosulfate followed by distillation from barium oxide. Both products show 99% deuteration. ... 

Base-catalyzed proton abstraction from trimethylsulfoxonium halides (1) with formation of dimethylsufoxonium methylide (2) was described by Corey in 1962. Solutions of (2) in dimethyl sulfoxide are conveniently prepared from the chloride or iodide (1) by stirring with one equivalent of sodium hydride at room temperature. 

To a solution consisting of 1 g (4.6 mmoles) of trimethylsulfoxonium iodide in 20 ml dry dimethyl sulfoxide is added 110 mg (4.6 mmoles) of sodium hydride powder or an equivalent amount of 50 % sodium hydride in mineral... 

Copper-mediated coupling of the aryl iodide derived from l,3-bis(2-hydroxy-hexafluoroisopropyl)benzene with perfluorooctyl iodide gives the desired compound as a dimethyl sulfoxide (DMSO) complex [166] (equation 143) Even bromoarenes can be coupled [167] (equation 144)... 

In a similar reaction, iodine fluonde also can be removed from perfluorobutyl-, perfluorohexyl-, and perfluorooctyl iodide by using zinc-copper couple in dimethyl sulfoxide or dimethylformamide [71]... 

Reaction of bisphenol with chloronitroaromatic compounds was generally performed in dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) at reflux using K2C03 as a base.108 109 It is possible to achieve this condensation in Ullmann s conditions by using a cuprous chloride or iodide-pyridine system as a catalyst when this reaction is performed with deactivated aromatic compounds, it gives too poor yields110 ultrasounds can dramatically improve yields without solvent.111... 

N-Bromosuccinimide purchased from Arapahoe Chemical Company was used without purification. If the purity of the N-bromosuccinimide is in doubt, it should be titrated before use by the standard iodide-thiosulfate method and purified, if necessary, by recrystallization from 10 times its weight of water. Solutions of N-bromosuccinimide in dimethyl sulfoxide cannot be stored, since the solvent is oxidized by the brominating reagent. 

Glycosyl-linkages were determined by GC-EIMS of the partially methylated alditol acetates. RG-II samples (2 mg) were methylated using sodium methyl sulfmyl carbanion and methyl iodide in dimethyl sulfoxide [24] followed by reduction of the uronosyl groups with lithium triethylborodeuteride (Superdeuteride , Aldrich) [23,25]. Methylated and carboxyl-reduced samples were then submitted to acid hydrolysis, NaBIlt reduction and acetylation, partially methylated alditol acetates being analysed by EIMS on two fused-silica capillary columns (DB-1 and DB-225) [20]. 

Dimethyl sulfoxide (DMSO), reagent grade Methyl iodide, reagent grade Silica gel (Merck)... 

Pure dimethyltriazanium chloride decomposes at 133 to 134° (the checker reports 135 to 136°). The salt is very hygroscopic and should be stored in a desiccator. It is readily soluble in water, methanol, ethanol, and dimethyl sulfoxide. An aqueous solution is stable at room temperature. Free iodine is liberated from an acidic iodide solution, and this reaction makes it possible to determine the triazanium content.3... 

The relatively minor alteration in reaction conditions can be seen to drastically alter the nature of the product (468). In addition many sulfoxide complexes are thermally degraded, and in consequence the extent of drying can alter the nature of the product. Thus, the complex [Co(0-Me2SO)8][I]2 is isolated from a cobaltous iodide-dimethyl sulfoxide system, but extensive drying in vacuo causes degradation to yield [Co(0-Me2SO)6][CoI4] (128). 

The proportion of C-alkylation increases in the order OTs < Br < I, a sequence which is often associated with the balance of hardness between nucleophile and nucleofuge (Smith and Hanson, 1971). The work of Kurts et al. (1974) indicates that the overall reaction rate of the crown ether-assisted alkylation increases in the order Na+ < K+ < Rb+ < Cs+, which, according to these authors, reflects the increasing distance between cation and anion in the ion pairs. The high reactivity of the tetraphenylarsenate also fits in with this picture. The decrease of the kc/k0 ratio is only small in good cation-solvating solvents such as dimethyl sulfoxide (DMSO). Alkylation of the sodium derivative of [103] with ethyl iodide in DMSO gave kc/kQ = 15.7 addition of... 

Isopropylidene N-substituted aminomethylenemalonates (442, R1 = R2 = Me) were methylated with methyl iodide in dimethyl sulfoxide in the presence of sodium hydride at room temperature overnight to give the N-methyl derivatives (1615) in 56-90% yields [88JCS(P )863,88JCS(P2)759]. 

A calculated transition energy used to assess the polarity of a solvent. The solvent ionizing capability directly affects the position of a peak, easily measured, in the ultraviolet region of the spectrum of the complex of an iodide ion with 2-methyl- or l-ethyl-4-carbomethoxypyridinium ion. Water has a Z value of 94.6, ethanol has a value of 79.6, dimethyl sulfoxide s value is 71.1, and benzene has a value of 54. A similar polarity scale, known as x(30) values, is related to the Z value scale Z = 1.41 t(30) -E 6.92. See Solvent Effects... 

The methylthiomethyl (MTM) group is a related alcohol-protecting group. There are several methods for introducing the MTM group. Alkylation of an alcoholate by methylthiomethyl chloride is efficient if catalyzed by iodide ion.9 Alcohols are also converted to MTM ethers by reaction with dimethyl sulfoxide in the presence of acetic acid and acetic anhydride10 or with benzoyl peroxide and dimethyl sulfide.11 The latter two methods involve the generation of the methylthiomethylium ion by ionization of an acyloxysulfonium ion (Pummerer reaction). 

---