Synthesis of Glycosides Other Than Pyranosides

Examples of the preparation of glycosides other than pyranosides by use of the Koenigs-Knorr reaction are rare compared with those of glycopyranosides. 

The glycofuranosides have been reviewed in this Series by Green.157 Several methods other than the Koenigs-Knorr method have been reported for the preparations of glycofuranosides. Glycosidation 

Ethyl /3-D-glucofuranoside164 was obtained by the reaction of 1,2-O-isopropylidene-a-D-glucopyranose 5,6-carbonate with ethanol in the presence of hydrogen chloride, followed by hydrolysis with sodium hydroxide. 

Aryl glycofuranosides have generally been prepared by fusion of the corresponding furanose acetates with the appropriate phenol in the presence of p-toluenesulfonic acid or zinc chloride.165-169 

Fletcher and coworkers170-172 found that phenyl and methyl j8-D-ribofuranoside (1,2-trans) are obtained by treatment of 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide with sodium phenoxide and meth-oxide, respectively, whereas favored formation of /3-D-arabinofurano- 

---