Rearrangement sulphenate-sulphoxide

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. 

Braverman and Grendi206 have shown that, depending on the type of substitution, allylic trichloromethanesulphenates undergo rearrangement to allylic trichloromethyl sulphoxides by one of two different pathways (equation 85). Rearrangement according to route a has been observed with allyl, crotyl and a, a-dimethylallyl sulphenates. It occurs... 

Reaction of alkynols 156 with benzenesulphenyl chloride afforded either the vinylacety-lene sulphoxides 157 or the allene sulphoxides 158 depending upon the substitution pattern of alkynols 156. Vinylacetylene sulphoxides 157 result from a [2,3]-allylic rearrangement of the sulphenate ester 159 (equation 88). In the case of the cyclic... 

Polychloromethylsulphonylbiphenyls, mass spectra of 154, 155 Polyenes, synthesis of 771 Polymerization, of sulphoxides 846 Polymer-supported reagents 928 Polymorphonuclear leukocytes 854 Poly(olefin sulphonejs, radiolysis of 916-922 Polysulphones, radiolysis of 913 Population analysis 14, 15, 21, 22 Propargylic sulphenates, rearrangement of 736-739... 

Rearrangement of acetylenic sulphenates to the allenic sulphoxides 151 was discovered when the synthesis of propargylic ester of trichloromethanesulphenic acid 152 was attempted (equation 86). This reaction is of general scope and gives very good yields of allenic sulphoxides (Table 14) from structurally diverse cohols and various sulphenyl chlorides Reaction of alkynols 153 with benzenesulphenyl chloride in the presence... 

Reaction of the carbanion of chloromethyl phenyl sulphoxide 409 with carbonyl compounds yields the corresponding 0-hydroxy adducts 410 in 68-79% yield. Each of these compounds appears to be a single isomer (equation 242). Treatment of adducts 410 with dilute potassium hydroxide in methanol at room temperature gives the epoxy sulphoxides 411 (equation 243). The ease of this intramolecular displacement of chloride ion contrasts with a great difficulty in displacing chloride ion from chloromethyl phenyl sulphoxide by external nucleophiles . When chloromethyl methyl sulphoxide 412 is reacted with unsymmetrical ketones in the presence of potassium tcrt-butoxide in tert-butanol oxiranes are directly formed as a mixture of diastereoisomers (equation 244). a-Sulphinyl epoxides 413 rearrange to a-sulphinyl aldehydes 414 or ketones, which can be transformed by elimination of sulphenic acid into a, 8-unsaturated aldehydes or ketones (equation 245). The lithium salts (410a) of a-chloro-/ -hydroxyalkyl... 

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. 

It has also been shown that reagents of type (45) in which the double bond is cis afford higher yields and greater stereoselectivity than the corresponding irons compounds [57], The cis (150) product prepared in this way could be isomerised to the required irons 15a product via a [2,3]sigmatropic rearrangement of a sulphenate ester to a 13-sulphoxide-14,15-m/ns-compound, and then treatment with trimethyl phosphite. 

Further studies of the formation of sulphoxides from sulphenates have been reported, by a [2,3]sigmatropic rearrangement (93) to (94), and unexpectedly from the reaction of cyclohexen-l-ol with phenylsulphenyl... 

A combination of [4 + 2] cycloaddition and [2,3]-sigmatropic rearrangement has been used with effect in the synthesis of hasubanan derivatives. Thus the 1-butadienyl phenyl sulphoxide (456) reacts with the enamine (457) to yield (458) as a mixture of diastereoisomeric sulphoxides. Heating (458) in the presence of a thiophilic species drives the equilibrium over to the sulphenate ([2,3]-sigmatropic shift) as the latter is converted into the amino-alcohol (459). This annelation sequence may also be used with electron-deficient dienophiles by employing 1-butadienyl phenyl sulphide (460). ... 

The addition products of [l,3-bis(phenylseleno)allyl]lithium and electrophiles may be converted, in high yields, into unsaturated aldehydes, this now being the subject of a full paper. The versatile sulphoxide-sulphenate rearrangement provides the regio- and stereo-control in a route to -substituted ( )-l-aryl-enones (Scheme 30). -Substituted enones may also arise from alkylation of... 

This behaviour is illustrated in a preparation of the 2-thioxopenam (258) from the sulphoxide (259). Thus, pyrolysis of (259) induces a sulphoxide-sulphenate ester rearrangement followed by intramolecular trapping to give the disulphide (260) which is converted in two steps into the penam (258). ... 

In contrast, the reverse of the sulphoxide-sulphenate ester rearrangement forms the basis for the synthesis of the dienes (261) and (262) and the enamine (263). The diene (261) is obtained via two consecutive 2,3-sigmatropic rearrangements when the butynediol (264 X = H) is treated with PhSCl-NEta, whereas diene (262) is formed after one 2,3-rearrangement from the mono-acetylated butynediol (264 X = Ac). When the same reagent combination is used with the propargyl alcohols (265) a similar 2,3-rearrangement occurs and... 

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