Sulfoxide, dimethyl reagents

Derived reagents. Mancuso and Swern2 have reviewed activated dimethyl sulfoxide reagents (100 references). Activation of DMSO with cither trifhioroacelic anhydride (7, 136) or oxalyl chloride (8, 200) provides the most generally useful... 

In this work, we used the dyes provided by the Research Center NllKHlMFOTOPROEKT and commercial chicken DNA (Reanal, Himgary) [7]. DNA concentrations were determined using the extinction coefficient of a base pair of 13200 1 moE cm at a wavelength of 250 nm [8]. An aqueous phosphate buffer solution (pH 7, at a concentration of 20 mmol l ), isopropanol, methanol, isopropanol, hexanol and dimethyl sulfoxide (reagent grade) were used as solvents. 

C-Alkylation Diethyl sulfate. Dimethyl sulfate. Dimethyl sulfoxide reagent (a). Methyl bromide. Methyl chloride. Nitrosonium hexafluorophosphate. Potassium r-butoxide. Sodium amide, Sodium ethoxide. Sodium 2-methyl-2-butoxide. Tetramethylurea. Tri-ethyloxonlum fluuruburate. Trimcthyloxonium fluurubomte. Trimethyloxonium 2,4,6-trlnltrobenzene lulfonale. Triiyliodium. 

Shen T, Huang X, Liang YF, Jiao N (2015) Cu-catalyzed transformation of alkynes and alkenes with azideand dimethyl sulfoxide reagents. Oig Lett 17(24) 6186-6189... 

The widely used Moifatt-Pfltzner oxidation works with in situ formed adducts of dimethyl sulfoxide with dehydrating agents, e.g. DCC, AcjO, SO], P4O10, CCXTl] (K.E, Pfitzner, 1965 A.H. Fenselau, 1966 K.T. Joseph, 1967 J.G. Moffatt, 1971 D. Martin, 1971) or oxalyl dichloride (Swem oxidation M. Nakatsuka, 1990). A classical procedure is the Oppenauer oxidation with ketones and aluminum alkoxide catalysts (C. Djerassi, 1951 H. Lehmann, 1975). All of these reagents also oxidize secondary alcohols to ketones but do not attack C = C double bonds or activated C —H bonds. 

Suitable strong bases include the sodium salt of dimethyl sulfoxide (m dimethyl sulfox ide as the solvent) and organohthmm reagents (m diethyl ether or tetrahydrofuran)... 

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. 

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. ... 

The use of dimethyl sulfoxide-acetic anhydride as a reagent for the oxidation of unhindered steroidal alcohols does not appear to be as promising due to extensive formation of by-products. However, the reagent is sufficiently reactive to oxidize the hindered 11 j -hydroxyl group to the 11-ketone in moderate yield. The use of sulfur trioxide-pyridine complex in dimethyl sulfoxide has also been reported. The results parallel those using DCC-DMSO but reaction times are much shorter and the work-up is more facile since the separation of dicyclohexylurea is not necessary. Allylic alcohols can be oxidized by this procedure without significant side reactions. 

An alternate ethynylating reagent is the lithium acetylide-ethylene-diamine complex which is available commercially. This reagent in dimethyl sulfoxide solution has been used to ethynylate 11 j -hydroxyestrone and its 3-methyl ether. 

Dimethyl sulfoxide reacts with trifluoroacetic anhydride at low tempera ture to give a complex that is an efficient reagent for the oxidation of alcohols to carbonyl compounds [40 41] This reagent can be used to oxidize primary and secondary aliphatic alcohols, cycloalkyl alcohols, and allylic, homoallylic, ben-zylic, acetylenic, and steroidal alcohols (equation 19)... 

The ionic species 5, as well as 6, represent the so-called activated dimethyl sulfoxide. Variants using reagents other than oxalyl chloride for the activation of DMSO are known. In the reaction with an alcohol 1, species 5, as well as 6, leads to the formation of a sulfonium salt 7 ... 

On treatment with a strong base such as sodium hydride or sodium amide, dimethyl sulfoxide yields a proton to form the methylsulfinyl carbanion (dimsyl ion), a strongly basic reagent. Reaction of dimsyl ion with triphenylalkylphosphonium halides provides a convenient route to ylides (see Chapter 11, Section III), and with triphenylmethane the reagent affords a high concentration of triphenylmethyl carbanion. Of immediate interest, however, is the nucleophilic reaction of dimsyl ion with aldehydes, ketones, and particularly esters (//). The reaction of dimsyl ion with nonenolizable ketones and... 

In practice, few alkenes are soluble in water, and bromohydrin formation is often carried out in a solvent such as aqueous dimethyl sulfoxide, CH3SOCFI3 (DMSO), using a reagent called W-brornosuccinimide ( rBS) as a source of Br2. NBS is a stable, easily handled compound that slowly decomposes in water to yield Br2 at a controlled rate. Bromine itself can also be used... 

The submitters dried dimethyl sulfoxide using Linde type 3A molecular sieves. The checkers distilled this reagent from calcium hydride at 10 mm. prior to use. 

Dimethyl sulfoxide from the J. T. Baker Chemical Company (reagent-grade) was used as supplied. 

In dimethyl sulfoxide (DMSO) the isomer ratios for aryl-de-diazoniation of 4-nitrobenzenediazonium ions demonstrate that the 4-nitrophenyl radical is the arylating reagent (Gloor et al., 1972 see Sec. 8.2). 

Corey and Chaykovsky had discovered that dimethyl sulfoxide is converted to methyl-sulfinyl carbanion upon treatment with sodium hydride114 and that this conjugate base of DMSO reacts with various electrophiles115. This finding has opened up various reactions with a-sulfmyl carbanions derived from sulfoxides, since the sulfinyl function can be removed either by thermolysis or by subjecting the compound to reductive desulfurization. Thus a-sulfmyl carbanions have become versatile synthetically useful reagents. 

It was shown in the same article that the decarboxylation could also be performed by conventional heating but then copper cyanide was required and a mixture of saturated and imsaturated 2-pyridones 65 and 66 was obtained in a ratio of 1 10 (Fig. 10). A tentative mechanism was suggested for the reagent-free MAOS method where the carbonyl in the 2-pyridone ring is supposed to assist in the decarboxylation yielding an yUde 67 (Fig. 11). The decarboxylated bicyclic 2-pyridone 68 is thereafter obtained after protonation by the solvent. In agreement with the mechanistic suggestion, it was shown that a selective deuteration occurred when deuterated dimethyl sulfoxide (DMSO-de) was used as solvent. 

A mixture of silver nitrate and dimethyl sulfoxide is stirred vigorously for co. 1 hour to dissolve all of the salt. Reagent-grade dimethyl sulfoxide was used without purification. 

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. 

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

Alkyltriphenylphosphonium halides are only weakly acidic, and a strong base must be used for deprotonation. Possibilities include organolithium reagents, the anion of dimethyl sulfoxide, and amide ion or substituted amide anions, such as LDA or NaHMDS. The ylides are not normally isolated, so the reaction is carried out either with the carbonyl compound present or with it added immediately after ylide formation. Ylides with nonpolar substituents, e.g., R = H, alkyl, aryl, are quite reactive toward both ketones and aldehydes. Ylides having an a-EWG substituent, such as alkoxycarbonyl or acyl, are less reactive and are called stabilized ylides. 

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