S-glycoside

Sugar peracetates treated with raethyIthiotrimethylsilane and boron 

Cinnamyl 1-thioglycosides have been made from 1-thlourea analogues by use of 2-bromostyrene in a study of inhibition of 

The catabolism and biological properties of the glucosinolates have been reviewed.  

An efficient synthesis of 4-methylphenyl 1,2-trans-l-thioglycopyranosides has involved isomerization of a mixture of the peracetylated endo- and exo-l,2-thio-orthoesters with deactivated Raney nickel and a trace of 4-methylthiophenol in toluene.1,2,3,5-Tetra-O-acetyl-P-D-ribofuranose reacted with thiophenol in the presence of tin(iv) chloride to give a mixture of S-glycosides containing principally phenyl 2,3,5-tri-O-acetyl-l-thio-p-D-ribofuranoside.  

An interesting photochemical rearrangement of an S-glycoside having a heterocyclic aglycone to a C-glycoside is mentioned in the next section. The conversion of acylated phenyl 1 -thiohexopyranosides into the corresponding phenyl 1 -thiohex-1 -enopyranosid-3-uloses is discussed in Chapter 12, and other references to S-gly-cosides will be found in Chapters 10 and 21. 

Three new C-(2-0-cinnamoyl-P-D-glucopyranosyl)flavones [ e.g. (70)] have been isolated from the leaves of Gentiana punctata while the leaves of G. asclepiadea 

Luong and A. Jacot-Guillarmod, Helv. Chim. Acta, 1977,60,2099. 

The uses of S-glycosides in several syntheses of 0-glycosides are noted in the preceding section. 

These compounds are currently attracting extremely wide interest, especially since members of the class are related to many components of other natural products. 

The use of S-phenyl-l-thioglycosides to prepare glycosyl fluorides and hence complex glycosidic products has been further 99 100 

1 Pyranold Compounds.- A review on the formation of C-C bonds by radical reactions Involving organotin or organomercury compounds includes instances of the synthesis of C-glycosides by this approach. 

Penta-O-acetyl-6-D-glucopyranose with allyltrimethylsilane and boron trifluoride gave the corresponding a-C-allyl glycoside in 8l% yield and high selectivity when the reaction was carried out in acetonitrile in 1,2-dichloroethane, however, the a- and 3-anomers were produced in equal proportions.  

Ring closures of appropriate hydroxyalkenes also provide access 

Reference to the use of the diene (45) in the synthesis of part of the complex marine toxin brevetoxin B is made in Chapter 24. Compounds (46) and (47) have been made following hetero-Diels 

1 Pyranold Compounds.- The use of glycosyl fluorides in the synthesis of C-glycosides has been covered in a review on fluorinated carbohydrates, and the work of Sinay s group on C -glycoslde synthesis from 1-llthlo derivatives and from glycosyl phenylsulphones has appeared in the form of a published lecture. 

Nicolaou et al have used the glycal triether (53a) in related 

A set of C-glycosides have been made from a trlchloroacetlmidate 1U6 

Benzylated glycosyl fluorides react with trimethylsilyl cyanide 

Other syntheses Include C-B-D-glycopyranosylmethylamines derived from lactose, cellobiose and maltose, produced by ferrous hydroxide reduction of the previously reported glycosylnitromethanes (Vol.16, p.42, ref.l86), C-glycosylbarbiturates, e.g.,(56), produced by reaction of free sugars in aqueous solution with barbituric acids and the C-linked disaccharide (57) synthesized by a novel radical 

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Glycosides are a large and very important class of carbohydrate derivatives character ized by the replacement of the anomeric hydroxyl group by some other substituent Gly cosides are termed O glycosides N glycosides S glycosides and so on according to the atom attached to the anomeric carbon... 

Sinignn (an S glycoside contributes to the characteristic flavor of mustard and horseradish)... 

Table 2.2 Synthesis of 1,2-c/s-glycosides by using glycosyl fluorides as glycosyl donors promoted by SnCI2-AgCI04 [6] or SnCI2-TrCI04 [7],...

This report deals with the synthesis and biological evaluations concerning photodynamic therapy properties of porphyrinyl- and dihydroporphyrinyl-type sugar derivatives. The chosen conjugates have O- and >S-glycosidic moieties or ether and ester functions. 

Two series of -glycosylated porphyrins have also been designed the derivatives from protoporphyrin-IX derivatization and the meso-aiy substituted porphyrins.81 83 The most comum S -glycosidic moieties on these glycoporphyrins are derived from thioglucose, thiomannose and thiogalactose. 

The conformational properties of a glyconucleoside containing an. S -glycosidic linkage have been also studied and compared to those of the corresponding O-disaccharide. A / and NOE data examination allowed a full pseudorotational analysis, showing a switch in the conformational preferences between the two molecules, the natural and the mimetic one.59... 

Building on the observations of Kahne and Takahashi, Chenault and Castro relied on the selective activation of an isopropenyl glycoside donor with TMSOTf, followed by subsequent activation of a second n-pentenyl glycoside with NIS/TESOTf.12 This one-pot glycosylation offers proof of the concept that Fraser-Reid s glycosides can be incorporated into one-pot syntheses. (See Scheme 11.7.)... 

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