Dialkyl sulphoxides synthesis

Some limitations of the subject surveyed have been necessary in order to keep the size of the chapter within the reasonable bounds. Accordingly, to make it not too long and readable, the discussion of the methods of the sulphoxide synthesis will be divided into three parts. In the first part, all the general methods of the synthesis of sulphoxides will be briefly presented. In the second one, methods for the preparation of optically active sulphoxides will be discussed. The last part will include the synthetic procedures leading to functionalized sulphoxides starting from simple dialkyl or arylalkyl sulphoxides. In this part, however, the synthesis of achiral, racemic and optically active sulphoxides will be treated together. Each section and subsection includes, where possible, some considerations of mechanistic aspects as well as short comments on the scope and limitations of the particular reaction under discussion. 

The synthesis of chiral dialkyl sulphoxides of high optical purity from dia-stereoisomeric alkanesulphinates has a serious limitation because the sulphinates are not... 

The reactions between PCI5 and alkenes or alkynes have already been discussed extensively in connection with the synthesis of a variety of phosphonic acid types (as their acid dichlorides). Successful applications have also used alkenyl alkyl sulphides (to give the dichlorides 381) to an enyne (to give the dichloride 382) and to RSC CCl (to give 383)584,585 variation of the Pummerer reaction consists in the interaction of PCI5 and a dialkyl sulphoxide, during which a trichlorophosphonium salt intermediate is decomposed with SO2 to yield a (2-alkylthioethenyl)phosphonic dichloride (Scheme 34). ... 

Photochemical synthesis of sulphoxides was reported for the first time by Foote and Peters111 in 1971. They found that dialkyl sulphides undergo smoothly dye-photosensitized oxidation to give sulphoxides (equation 32). This oxidation reaction has been postulated to proceed through an intermediate adduct 63, which could be a zwitterionic peroxide, a diradical or cyclic peroxide, which then reacts with a second molecule of sulphide to give the sulphoxide (equation 33). 

A high yield synthesis involving formal oxidation of a sulphoxide to a sulphoximine has been reported183 using O-mesitylenesulphonyl hydroxylamine (NH2OMes) (equation 67). The reaction is successful for a wide range of sulphoxides including dialkyl, diaryl and cyclic species. 

A direct synthesis of dialkyl sulphide derivatives of B12H1 has been reported, using dimethyl sulphoxide and acetic anhydride, thus ... 

Sulphinyl ylides, the carbanions obtained from sulphoxides by proton abstraction, continue to be of limited use in organic synthesis but of increasing interest in stereochemical studies. The thioacetal monosulphox-ide (95) could be dialkylated in the presence of n-butyl-lithium, then cleaved with HgCh to afford a ketone. The monoalkylation product could be intercepted readily, thus permitting the effective dialkylation of C=0 and a novel initiated synthesis of ketones. The stereochemistry of the methyla-tion of 4-t-butyl-l-thiacyclohexane oxide depends on the orientation of the sulphoxide oxygen. Using methyl iodide or trideuteriomethyl iodide in the... 

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