Sulfenate esters, propargyl

Two different types of substrates are used here, propargyl sulfenates and propargyl sulfmates. In both cases often the propargylic esters are prepared and then converted to the allenes in situ. 

The [2,3]sigmatropic rearrangement of propargylic sulfenates can be applied for the preparation of a variety of functionaUzed allenes, not readily acceptable by other routs. Thus, a number of suMnyl allenecarboxy-lates (67, 68), as new 1,1-diacceptor-substituted allenes, were prepared via a [2,3]sigmatropic rearrangement of the corresponding sulfenate esters (65, 66) (Scheme 16) [49,50]. 

Certain sulfoxides can be prepared by rearrangement of the sulfenate esters thus, allyl arenesulfenate esters (7), obtained by condensation of the sulfenyl chloride with allyl alcohol (8), spontaneously rearrange to the allyl sulfoxides (9) (Scheme 6). The rearrangement also occurs with alkynic alcohols for instance, trichloromethanesulfenyl chloride (10) reacts with propargyl alcohol (11) to form the allenic sulfoxide (12) (Scheme 7). 

A mercury-free route to allyl vinyl ethers that relies on the Michael addition of allyl alcohols to unsubstituted alkenyl sulfoxides, followed by thermal loss of sulfenic acid and concurrent Claisen rearrangement has been described [145]. This methodology has been applied to the synthesis of isocar-bacyclin [146]. Posner reported an acid-catalyzed protocol that produces conjugated dienoate esters from allylic alcohols and a sulfinyl orthoester [147]. Additionally, the use of propargyl alcoholates and a chloro alkenyl sulfox-... 

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