Sulfur-containing groups ylides

In addition to sulfur ylides, examples are known of cyclopropanations using other ylides containing group V or group VI elements. Among these, triphenylphosphonium ylides have most frequently been studied. Some examples are collected in Table 19. The products obtained in entries 1-3 and 10 of Table 19 are suitable precursors for chrysanthemic acid. An enantioselec-tive synthesis of cyclopropanes was achieved by using electron-deficient alkenes substituted with an optically pure oxazolidine or acetonide function. When the alkene is stabilized by a ketone or nitro function instead of an ester function, the yield dropped considerably. 

Sulfur ylides containing a benzylic group (analogous to 19) undergo an analogous rearrangement.254... 

If opportunity is given, a (thiolated) carbon atom can be transferred from a sulfur ylide to a double bond with diastereocontrol. The carbon remains on that side of the molecule which contained the sulfur initially e.g. equation 40). By similar chirality transfer, the (3-oriented phenylthio group of octalin (147) determines the -orientation of the transposed PhSCH2 unit in the reaction product (148 equation 41). The efficient formation of a quaternary center from (147) is all the more remarkable since an... 

Sulfur ylides containing only alkyl, vinyl or aryl groups are very unstable and must generally be generated and used at low temperatures (approximately -70°C). On the other hand, ylides containing carbonyl, cyano, nitro or sulfonyl... 

Condensing sulfoxides with compounds containing reactive methylene groups gives sulfur ylides in good yields ... 

---