Reactions of Oxysulphonium Ylides

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

Two alkylations have been reported. The conjugated ylide (65) reacted with methyl iodide presumably first to form the oxysulphonium salt, which 

Mukaiyama, M. Higo, and H, Takei, Bull, Chem. Soc. Japan, 1970, 43, 2566. 

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 

Dimethyloxysulphonium-methylide reacts with conjugated olejfins to transfer a methylene group and form a cyclopropane. Thus, 1-nitro-prop-l-ene afforded fra/ij-l-nitro-2-methylcyclopropane. Speckamp et fl/. and Tsuge and Shinkai reported similar reactions for a-benzylidenecycloalkanones. The overall more complex reactions with griseofulvin and with isoderritol probably commenced by a similar conjugate addition. Johnson et al have reported that the methylide (59) 

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 

Tamura, T. Miyamoto, T. Nishimura, and Y. Kita, Tetrahedron Letters, 1973, 2351. 

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 

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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). 

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)]. ... 

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. 

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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