Thioglycosides, from thioacetals

Little preparative importance attaches to conversion of organic sulfides into chloro compounds The fission of compounds R-S-R by chlorine, bromine, cyanogen bromide, and methyl iodide, with replacement of C-S by C-halogen bonds has been reviewed by Tarbell and Harnish.1287 The action of 1 mole of bromine on thioacetals in an anhydrous medium (ether) at room temperature affords bromo hemiacetals (a-bromo sulfides) and a sulfenyl bromide, and bromo sugars analogously from ethyl thioglycosides. 

Indirect formation of thioglycosides can also be performed from glycosyl halides. Reaction with thiourea yields a pseudothiouronium salt, which (as the thioacetate above) can be hydrolyzed under mild, selective conditions to give the anomeric thiol, which then can be alkylated in an efficient, non-smelling procedure to produce... 

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