From Glycosyl Halides

A convenient preparation of 2-deoxy sugars [204] from glycosyl halides is based on the rapid and irreversible migration of an acyloxy group from C-2 to the anomeric center upon generation of the glycosyl radicals. This is a thermodynamically controlled reaction because it restores a d-a-d arrangement. 

Tropper, F Andersson, F., Braun, S., and Roy, R. (1992) Phase transfer catalysis as a general and stereoselective entry into glycosyl azides from glycosyl halides. Synthesis 618-620. 

In the case of organochromium(III) complex intermediates obtained from glycosyl halides, work by Somsak and coworkers showed that their decay into glycals [75] is marked by the remarkable stability of the organometalic compounds in aqueous solutions. From the same group came the radically new concept of using zinc metal under aprotic conditions [76]. In brief, they proposed that acetylated glycosyl bromides be treated with zinc dust in the presence of A-heterocyclic bases (e. g., 4-methylpyridine or 1-methylimidazole) in a variety of aprotic solvents (i. e., benzene, ethyl acetate, tetrahydrofuran, acetone, dichloromethane) to afford the... 

Due to the interest in thioglycosides, the methods of their synthesis from glycosyl halides with thio-lates or by S-alkylation of 1-thioaldoses have been complemented by new methods. ... 

Koenigs-Knorr glycosidation Synthesis of alkyl or aryl O-glycosides from glycosyl halides and alcohols or phenols, respectively. 246... 

Some of the most important syntheses of glycosides start from glycosyl halides, which are converted into acetylated glycosides, with Walden inversion, by reaction with alcohols or phenols in the presence of acid-binding compounds. For example, methyl tetra-0-acetyl-/ -D-glucoside is obtained from a-aceto-bromoglucose by this method (the Koenigs-Knorr reaction) 942... 

Synthesis of Glycosyl Azides from Glycosyl Halides 104... 

A. Stimac and J. Kobe, Stereoselective synthesis of 1,2-cts-and 2-deoxyglycofuranosyl azides from glycosyl halides, Carbohydr. Res., 329 (2000) 317-324. 

The olefin metathesis reaction as applied to carbohydrate dienes has been reviewed, as has the use of titanocene(III) and zirconocene(III) chlorides as mild reagents for generating 1-glycosyl radicals from glycosyl halides, and converting them into glycals. ... 

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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