Dimethylsulfonium chloride

In a series of studies of the reactions of charged substrates, the nucleophilic substitution reactions of (4-methoxybenzyl)dimethylsulfonium chloride have been... 

The first step of the mechanism of the Corey-Kim oxidation is the reaction of dimethylsulfide with A/-chlorosuccinimide to generate the electrophilic active species, S,S-dimethylsuccinimidosulfonium chloride Corey-Kim reagent) via dimethylsulfonium chloride. The sulfonium salt is then attacked by the nucleophilic alcohol to afford an alkoxysulfonium salt. This alkoxysulfonium salt is deprotonated by triethylamine and the desired carbonyl compound is formed. The dimethylsulfide is regenerated, and it is easily removed from the reaction mixture in vacuo. In the odorless Corey-Kim oxidation instead of dimethylsulfide, dodecylmethylsulfide is used. This sulfide lacks the unpleasant odor of DMS due to its low volatility. 

After clarification of the structural relation between BLM and PHM, the nephrotoxicity of PHM described earlier was reinvestigated. The PHM used for the toxicity tests was a mixture which contained appreciable amounts of BLMs B4 and B6. Bleomycins B4 and B6 showed strong nephrotoxicity in the dog. The BLM mixture isolated from the BLM fermentation contained only a small amount of BLMs B4 and B6 (Fig. 1). The above-mentioned facts suggested that the nephrotoxicity of PHM found earlier was not an intrinsic propertiy of PHM in general, but was due to the specific toxic components. To prove this, an artificial PHM, which has the same terminal amine as that of BLM A2, was prepared by fermentation added with (3-aminopropyl) dimethylsulfonium chloride as a precursor for the terminal amine30 and was examined for the toxicity. This artificial PHM showed no nephrotoxicity like BLM A2. Thus, it has been proved that the nephrotoxicity of PHM in the earlier experiment is not a property of PHM in general, but is due to the specific toxic component. 

Pyrrol-2-yl)dimethylsulfonium chlorides. Substitution at C-2 of pyrroles is accomplished in MeCN at 0 C. 

The synthesis of the PDPV precursor, poly (2,5-dimethoxy-l,4-xylene-a-dimethylsulfonium chloride) also followed the technique reported by by Karasz et al.i6 The bead coating procedure was identical except that doping was done above solid I2 at room temperatiue for 12 days. 

Treating dimethylsulfonium acetylcarbamoylmethylide (297) with isoquinoline IV-oxide in the presence of acetyl chloride in dimethylformamide gave a complex reaction mixture from which 4-methyl-3-methylthio-2//-pyrimido[2,l-a]isoquinolin-2-one (156) and sulfur ylide (236) were isolated in 5.9% and 19.2% yields, respectively (80YZ1261). 

Another remarkable synthesis of 2,4-dicarboxythiophenes in high yield involves a unique dimethylsulfonium butadiene (34), which could be cyclized to 2,4-dimethoxycar-bonylthiophene (35) in 91% yield by standing overnight in thionyl chloride (66CB1558). The crystalline salt (34) was obtained in satisfactory yields by refluxing two equivalents of methyl propynoate with one equivalent of dimethyl sulfoxide in ethanol. 

Dimethylsulfonium methylide. The reagent can be generated conveniently by reaction of NaOH with trimethylsulfonium chloride rather than NaH, required for generation from trimethylsulfonium iodide, the usual precursor.1 An added advantage is that the chloride can be prepared readily by reaction of dimethyl sulfide with methyl chloroformate in 73% yield.2... 

BUTENOLIDES D i methylformamide dimethyl acetal. Dimethylsulfonium methylide. Peracetic acid. Phenylthiomethyllithium. Titanium(IV) chloride. Trifluoroacetyl chloride. 

To a medium having a composition of 6.4 % of millet jelly, 0.5 % of glucose, 3.5 % of soybean powder, 0.75 % of corn steep liquor, 0.3 % of sodium chloride, 0.1 % of potassium secondary phosphate, 0.05 % of zinc sulfate, 0.01 % of copper sulfate, 0.2 % of sodium nitrate and 0.01 % of Toho No. 1 (trade name for a surface active agent composed of polyoxyethylene manufactured by Toho Chemical Industry Co. Ltd., Japan) was added 3-amino-propyl-dimethylsulfonium bromide hydrobromate in a proportion of 0.4 mg/ml to adjust the pH of the medium to 6.5. 

Construction of the suitably substituted geranic acid for making the furan ring has been effected too. For example, Poulter et al. have prepared the substituted geranate 865 by reaction of 4-methyl-3-pentenylcopper with the acetylenic ester 866. The ester 865 then underwent cyclization in the presence of acid to the lactone 867, related to scobinolide (161), and the action of acid on the lactol produced from 867 with diisobutylaluminum hydride gave perillene (849). The lactone 867 has also been prepared by a slightly different method the C9 alcohol 868 was made (in poor yield) from isobutenol and prenyl chloride with butyllithium. The extra carbon atom was introduced by the action of sodium cyanide on the epoxide of 868, and hydrolysis of the cyano group followed by dehydration yielded the lactone 867. The dimethylthioacetal of 867 has been used to synthesize perillene (849). This thioacetal was made from the suitably substituted ketene thioacetal 869 and dimethylsulfonium methylide. Thus the ketene thioacetal 870 (readily prepared from acetone, carbon disulfide, and sodium amylate, followed by methylation °) can be prenylated with lithium... 

N-Benzyl-N-methylephedrinium bromide. Diisopinocamphylborane. trans-2,4-Dimethoxymethyl-5-phenyloxazoline. (-)-N,N-Dimethylephedrinium bromide. Dimethylsulfonium methyUde. (-)-Menthoxyacetyl chloride. 2-Methyl-f-methoxy-methyl-5-phenyl-2-oxazoline. L-Proline. Quinine, chinchonine. 

Reagents other than oxalyl chloride, including trifluoroacetic anhydride, have been used to generate various dimethylsulfonium salts for reaction with the alcohol. 

---