Sulphoxides allyl

The ethylaluminium dichloride-catalyzed reaction of p-toluenesulphinyl chloride with alkenes 136 successfully applied191 for the synthesis of allylic sulphoxides 137 (equation 74) may also be regarded formally as a reaction of sulphinyl chlorides with compounds containing active hydrogen atom. Treatment of an alkene 136 with one equivalent each of ethylaluminium dichloride and p-toluenesulphinyl chloride at room temperature gave the corresponding 137. This reaction is very general and proceeds in... 

The spontaneous rearrangement of allyl p-toluenesulphenates to allyl sulphoxides was independently recorded by Mislow and coworkers and Braverman and Stabinsky. Mislow and colleagues201 have demonstrated that simple allyl alcohols such as 149, on conversion to the corresponding lithium alkoxides followed by treatment with arenesulphenyl chlorides, may be smoothly transformed at room temperature via the sulphenate esters into allylic sulphoxides 150 (equation 83). Braverman and Stabinsky202 have found that when the more reactive trichloromethanesulphenyl chloride is treated with allyl alcohol and pyridine in ether at — 70°, it affords trichloromethyl allyl sulphoxide and not allyl trichloromethanesulphenate as reported by Sosnovski203 (equation 84). 

The allyl sulphenate-allyl sulphoxide rearrangement is a general reaction and is applicable to structurally diverse allyl alcohols204,205 (Table 13). Mechanistically, it represents a typical example of a [2,3]-sigmatropic rearrangement as shown by the detailed investigations of Mislow and Braverman and their coworkers. 

Treatment of (—)-(S)-276 with allyl Grignard reagents gives optically active allylic sulphoxides 288. This reaction, however, involves an allylic rearrangement via transition state 289 as evidenced by Mislow and his collaborators362 (equation 160). 

The reaction of the phenylsulphinyl allylic lithium a-carbanion 342 with oxiranes was found by Guittet and Julia to give, after rearrangement and desulphurization, dihydroxy-dienes 343427 (equation 197). Demoute and coworkers have described the alkylation reaction of a very sophisticated 2-alkenyl sulphoxide 344 as a part of the total synthesis of a juvenile hormone 345428 (equation 198). Since the allylic sulphoxide carbanion has an ambident character, the alkylation may occur sometimes also at the y-position. This direction of alkylation is observed in the case of acyclic allylic sulphoxide anions 346, and results in the formation of the corresponding allylic sulphoxide 347 and vinylic sulphoxide 348423 (equation 199). 

Alkylcopper reagents add to allenyl sulphoxides 555 to give the corresponding allylic sulphoxides 556 in moderate yields647 (equation 354). 

Double bond migration in vinylic and allylic sulphoxides can be achieved by using proper bases B (equation 375). 

TABLE 13. Synthesis of allyl sulphoxides from sulphenyl chlorides, RSCl, and allyl alcohols... 

Dithioacetal monoxides undergo Michael addition to acrylonitrile. The addition products are easily converted into y-ketonitriles 382 (equation 221). Benzenesulphinyl allylic carbanions 383 derived from the corresponding allylic sulphoxides react selectively at the y-position with a variety of cycloalkenones to give the l,4-adducts " (equation 222). Recently, Nokami and coworkers have synthesized some prostaglandin analogues via a three-component coupling process involving 1,4-addition of phenylsul-phinyl allylic carbanion (equation 223) . ... 

Nucleophilic addition to allenyl sulphoxides 547 proceeds across the a, /(-double bond to produce the corresponding )3-substituted allylic sulphoxides which undergo readily a [2,3]-sigmatropic rearrangement affording substituted allyl alcohols (equation 345). Under proper basic conditions, the initially formed allylic sulphoxides can rearrange to the corresponding vinyl sulphoxides which can be elaborated to 2,4-dienones 549 (equation 346) and a-ketosulphoxides (equation 347) . ... 

Sulphoxides and selenoxides undergo syn elimination under thermal conditions. A 1,4-elimination of sulphenic acid from an allyl sulphoxide leads to dienes (equation 20)50. Precursor sulphoxides are generated by oxidation of corresponding sulphides. This reaction, however, did not give good results when applied to more complicated systems51. 

Where X is S or Se and Y is oxygen or a carbanionic site. The rearrangement of allyl sulphoxides to allyl sulphenates is an example. 

An example of a [2,3]-sigmatropic rearrangement involving an allyl sulphoxide was studied by Evans and Andrews in 1974 [22] (Scheme 5.20) ... 

Thermal and mercury(ii)-catalysed [3,3]sigmatropic rearangement of allylic trichloroacetimidates and allylic pseudo-ureas" e.g. geraniol, linalool) are useful for the 1,3-transposition of hydroxy- and amino-groups the former is synthetically preferred. The [2,3]sigmatropic rearrangement of allylic sulphoxides has been used to effect an alkylative 1,3-carbonyl transposition of enones (e.g. carvone). ... 

One of the most widely used allyl alcohol syntheses uses the Evans-Mislow rearrangement (39, arrows) of allyl sulphoxides17) (Scheme 1). Since the allyl sulphoxide is usually made from some allylic electrophile by substitution and oxidation, this strategy requires a specific allyl cation equivalent. 

Scheme 1, Allyl alcohol synthesis via allyl sulphoxides...

Substituents X and Y based on sulphur are particularly interesting. We have already seen that vinyl sulphides are latent ketones, that allyl sulphides form useful anions and that their sulphoxides give allyl alcohols. Evans17 has used cyclic allyl sulphoxide anions in an allyl alcohol synthesis, and has used the sulphoxide 148 in a Diels-Alder synthesis88 of the hasubanan derivative 149. 

The conjugated thionium ylids are prepared by the Pummerer reaction of an allyl sulphoxide, with trimethylsilyl triflate in the presence of ethyl diisopropylamine, and give products of ketone allylation [equation (52)... 

TiCl or by a Pummerer-type activation of allyl sulphoxide, may... 

The reactions shown above involve the main chain, but it is possible that sulphur-containing cross-links present in a vulcanizate are also sites for oxidative attack. Little is known about such processes except by analogy with simpler sulphides. The general thermal instability of allylic sulphoxides suggests that monosulphide cross-links may undergo the following reactions ... 

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