Allenic sulphoxides rearrangement

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... 

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... 

Heating compounds containing the system C C—C—S—C=C in hexa-methylphosphoramide (HMPA) gives 2if-thiopyrans (247). Isomeric thio-phens appear when the reaction is conducted in the presence of amines. Allene sulphoxides (248) are readily available by reaction of alkynols with sulphenyl chlorides to form labile sulphenyl esters, which rearrange to (248). The two chiral centres in these molecules (sulphoxide and allene) result in... 

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