Ketones dimethyl sulfoxide-iodide

Primary alkyl halides (chlorides, bromides, and iodides) can be oxidized to aldehydes easily and in good yields with dimethyl sulfoxide.311 Tosyl esters of primary alcohols can be similarly converted to aldehydes,312 and epoxides313 give a-hydroxy ketones or aldehydes.314 The reaction with tosyl esters is an indirect way of oxidizing primary alcohols to aldehydes (9-3). This type of oxidation can also be carried out without isolation of an intermediate ester The alcohol is treated with dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC),315 and anhydrous phosphoric acid.316 In this way a primary alcohol can be converted to the aldehyde with no carboxylic acid being produced. 

Methylation (666, 912) of 2-methoxypyrazine with methyl iodide in dimethyl sulfoxide at room temperature gave 3-methoxy-l-methylpyrazinium iodide with a rate of methylation relative to pyrazine of 1.05 (666). 2-Methoxypyrazine with tetracyanoethylene oxide gave a small yield of 3 ethoxypyrazinium dicyano-methylide (53) (1094). Alkylation of 2-methoxypyrazine with ethyl methyl ketone in the presence of sodium in liquid ammonia to give 2-s-butyl-6-methoxypyrazine (17%) has been described (614). The reactions of 3-hydroxy-2,5-dimethylpyrazine and alkylhalides have been examined (1095). 

Another variation on the same theme is the oxidation of a-bromo ketones by dimethyl sulfoxide in the presence of potassium iodide and sodium carbonate. In situ conversion of the bromo ketone into iodo ketone evidently facilitates the reaction, because it is successful even with secondary a-bromo ketones, with which simple oxidation fails. Depending on the steric environment, the reaction may occur at room temperature, but it may require a temperature of 120 C. Yields range from 71 to 95% (equation 413) [1005. ... 

Dimethyl sulfoxide-derived reagent (c). Dimethyloxosulfonium methylide, (C H. i)2S=C H 2. This more stable reagent introduced by Corey reacts with monofunctional carbonyl compounds to give epoxides (oxiranes), but with a,/3-unsaturated ketones it gives cyclopropyl ketones. In one procedure a mixture of 0.1 mole each of powdered sodium hydride and trimethyloxosulfonium iodide (I) - is placed in a three-... 

A quite different route to 1,4-diketones is based on the homo-coupling of aryl methyl ketones to produce 2-methylthio-l,4-di(aryl)but-2-ene-l,4-diones 7 using copper(ll) oxide, iodine and dimethyl sulfoxide. The reduction of the C-C double bond in 7 with potassium iodide and concentrated hydrochloric acid then produces... 

A soln. of phenacyl bromide in a little tetrahydrofuran added at -30 to -20° to dimethylsulfoxonium methylid prepared from trimethylsulfoxonium iodide and NaH in dimethyl sulfoxide, and stirred at room temp, overnight -> phenyl cyclopropyl ketone. Y 37%. Also with phenacyl tosylate and f. e. s. P. Bravo et al., G. 100, 566 (1970) Tetrahedron 27, 3563 (1971). 

Trichloro(methyl)silane-Sodium iodide, 11, 553-554. This in situ equivalent of io-dotrimethylsilane is also effective for cleavage of esters and lactones, selective conversion of tertiary and benzylic aleohols into iodides, dehalogenation of a-halo ketones, deoxygenation of sulfoxides, and conversion of dimethyl acetals to carbonyl compounds. ... 

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