Glycosyl thiocyanates, thioglycosides

Acylated glycosyl thiocyanates are made by treatment of acylated glycopyranosyl halides with potassium thiocyanate.30 Reaction at —40° with a Grignard reagent affords alkyl or aryl 1-thioglycosides.54... 

The glycosyl thiocyanates can be transformed into thioglycosides through cleavage to the thioaldose by treatment with sodium methoxide under mild conditions followed by alkylation, or by a Grignard reaction which directly gives the thioglycoside (mannose-a-D-thiocyanate was inert) (O Scheme 38) [138]. 

Other literature methods not described in detail here, utilise glycosyl sulfenate [41], thiopseudourea [42], xanthate [42, 43], thiocyanate [44, 45] and dithioacetal [44, 46] intermediates or rely on radical addition to thiohemiacetals [47, 48] or thermal decomposition of diazo compounds prepared by reacting 1-thioaldoses and aryl diazonium salts [44]. Some of these procedures have specific advantage in some specific cases, e.g. the dithioacetal to thioglycoside route is valuable for preparing 1-thio-hexofuranosides [46, 49]. 

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