Oxysulphonium Ylides

Oxysulphonium Ylides.—Reagents that are related to DMSO are now in routine use for the selective oxidation of alcohols to aldehydes and ketones. The particularly effective combination of DMSO and oxalyl chloride followed by triethylamine has been shown to involve the intermediacy of a chlorodimethylsulphonium salt (21).  

Ticozzi, G. Fronza, R. Bernard , and D. Maggi, Gazz. Chim. Ital., 1979, 109, 137 P. Bravo and C. Ticozzi, ibid., p. 169. 

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Synthesis and Properties.—The major limitation in the use of oxysulphonium ylides is the shortage of ylides other than the methylide. Virtually no progress has been made on this problem in the past two years, other than in the case of some very stabilized ylides. For example. Dost and Gosselck have expanded the reaction of stable diazo-compounds with DMSO to afford stable and isolable oxysulphonium ylides (58). 

Kunieda and Witkop have reported the cleavage of a substituted oxysulphonium ylide (62) with Raney nickel in the presence of other... 

Reactions of Oxysulphonium Ylides.— Numerous acylations have been reported, generally starting with the methylide. The formylmethylide (61)... 

No further elaboration of the very important reaction of oxysulphonium ylides with carbonyl compounds to afford oxirans has been reported in the past two years other than additional applications. Two rather unusual reports bear mention. Wiechert has reported the reaction of dimethyl-oxysulphonium-methylide with steroidal a-bromoketones, presenting the possibility of attack by ylide on the carbonyl group or on the carbon bearing the bromine. However, the products of the reaction were the two ketones (66) and (67) in the ratio 1 2. These products can be accounted... 

The various sulphur imines are isoelectronic with sulphonium ylides, oxysulphonium ylides, sulphur dioxide, sulphoxides, or sulphones. Their chemistry has been reviewed briefly by Field and extensively by Roesky. All such imines are dealt with here with the exception of the. S-Cdihalogeno)-N-substituted iminosulphuranes, for coverage of which readers are referred to the Roesky review and to two leading references. ... 

A similar deimination of sulphoximides by phenyl(trihalogenomethyl)mercury compounds and subsequent substitution by the carbene species also affords the corresponding oxysulphonium ylides [reaction (5)]. ... 

Synthesis and Properties.—Oxysulphonium ylide chemistry still suffers from the lack of a variety of simple, high-yield syntheses of the precursor... 

Full details now have appeared regarding the reactions of diazo-com-pounds with sulphoxides to form oxysulphonium ylides," a method analogous to that employed for sulphonium ylides. The reaction, in the presence of cuprous cyanide, seems effective only with disubstituted diazomethane in which both substituents are strongly electron-withdrawing. Dimethyloxysulphoniumcyclopentadienylide was prepared by this method from diazocyclopentadiene and DMSO. 

Reactions of Oxysulphonium Ylides.— The reaction of oxysulphonium ylides with carbonyl compounds to form oxirans remains an important synthetic tool. C. R. Johnson and his students have published details of many of the... 

Dimethyloxysulphonium-methylide has long been known to add to the olefinic group of a 3-unsaturated carbonyl compounds, and additional examples have been reported. Cyclopropane formation also has been reported from stabilized oxysulphonium ylides such as (85) and those carrying two stabilizing groups on the methylide carbon. The dienone (91) underwent double addition with (89) to form the syn-isomer only, but the... 

In one of the few alkylations known for oxysulphonium ylides, the phenacylide (93) underwent Oalkylation with trimethyloxonium ion to give a mixture of stereoisomers. Schmidbaur and Kapp °° have published... 

N-tosylimino-oxysulphurane. This ylide reacts in high yield with carbonyl compounds to afford oxirans in a reaction analogous to that effected by sulphonium or oxysulphonium ylides. Optically active phenylmethylsul-phoximine could be tosylated and converted into an ylide with sodium hydride in DMSO, and it reacted with acetophenone to afford optically active 1-phenyl-1-methyloxiran. The ylide (156 R = R = Me) also effected additions to conjugated carbonyl compounds, such as co-benzoylstyrene, to afford l-phenyl-2-benzoylcyclopropane. Johnson recently has reviewed the use of N-tosyliminosulphoxonium ylides in organic synthesis. 

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