Propargylic sulfonium ylides 2,3 sigmatropic rearrangements

Further study by Katsuki, McMillen, Hashimoto, and Wang improved the enantioselectivity up to a moderately high level.Wang and co-workers further extended the asymmetric catalysis to the [2,3]-sigmatropic rearrangement of propargyl sulfonium ylide to give allenic products with up to 81% ee (Equation (18))." ... 

Sigmatropic Rearrangements of Propargylic Sulfonium Ylides and Related Systems... 

Scheme 6 Iron-catalyzed carbene generation/[2,3]sigmatropic rearrangement of propargyl sulfonium ylides...

Scheme 7 [2,3]Sigmatropic rearrangement of propargyl sulfonium ylides as a ring forming reaction...

A more direct access to the unstable and non isolated sulfonium ylides 58a- c is the reaction of diisopropyl diazomethylphosphonate 57 with allylic sulfides, catalyzed by Cu(II), Rh(II) [39], or ruthenium porphyrins.[40] For example, the a-phosphorylated y,d-unsaturated sulfides 59-61 are obtained through the [2,3] -sigmatropic rearrangement of 58a-c. This method allows the use of a greater variety of starting allylic sulfide substrates, such as 2-vinyl tetrahydrothiophene, or propargylic sulfides (Scheme 15). 

The [2,3]sigmatropic rearrangement of sulfonium ylide (24) derived from rhodium-catalyzed decomposition of ethyl 3,3,3-trifluoro-2-diazopropanoate (23) in the presence of propargyl sulfide (22a) affords the corresponding functionalized CF3-containing carboxylic ester sulfide (25a). The latter was... 

Allenic sulfides (37) have been obtained with moderate to good enantio-selectivities (up to 81%) in sigmatropic rearrangements of sulfonium ylides generated from propargyl aryl sulfide (35) and aryldiazoacetates (36) as carbenoid source catalyzed by chiral Rh(ll) (38a,b) and Cu(l) (38c) catalysts [34] (Scheme 8). 

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