1-Thioglycosides alkenes

Acetylated 1-thioaldoses react with alkenes in the presence of azobis(isobuty-ronitrile) (AIBN) to give acylated alkyl 1-thioglycosides.55... 

J. M. Lacombe, N. Rakotomanomana, and A. A. Pavia, Free-radical addition of 1-thiosugars to alkenes. A new general approach to the synthesis of 1-thioglycosides, Tetrahedron Lett., 29 (1988) 4239-4296. 

In some cases the addition of electrophilic alkenes, such as 4-allyl-1,2-dimethoxybenzene, to the reaction mixture can improve the outcome of the reaction, particularly when run in the presence of thioglycosides, by scavenging a by-product of the reaction, phenylsulfenyl tritlate. Non-carbohydrate thioacetal sulfoxides also undergo similar acetalation reactions when treated with Tf20 (eq71).i ... 

Dithioacetal, Trithioorthoester, and Thioglycoside Activation. DMTSF provides a chemoselective reagent for dithioacetal activation in the presence of electron-rich alkenes. This bond-forming procedure complements the TiCLj mediated reaction between acetals and sUyl enol ethers demonstrated hy Mukaiyama. The generation of ketone precursors through dithioacetal carban-ion (acyl anion equivalents) chemistry further amplifies the significance of DMTSF activation. 

The chiral epoxide (50), obtained by Sharpless asymmetric eposidation of a racemic alkene, has been converted into the 2-deoxy-thioglycosides (51), which were obtained as a 1 1 anomeric mixture (Scheme 10) the a-thioglycoside was used in the... 

Radical addition of a 1-thiosugar to an alkene has been used in the preparation of a number of thioglycosides as exemplified in Scheme 4 with regard to the anomeric configuration of the... 

Martin and Zinke have given a full account of their synthesis of KDO in which the molecule is assembled around a furan template (see Vol. 23, p.162-3).39 The dithioacetal (35) of KDO (see also Vol. 23, p.161-2) can be subjected to iodonium-ion induced cyclisation to give access to, depending on the conditions, the thioglycoside (36) or the alkene (37) (36) can be used to make p-glycosides of KDO, whilst (37), when activated with phenylselenenyl triflate, acts as a precursor to a-glycosides. f Other references to glycosides... 

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