Anomeric isocyanides

In addition to the formation of anomeric nitriles, similar chemistry allows for the formation of anomeric isocyanides. Requirements for these reactions include utilizing acetates, halides, and imidates as activating groups. Some Lewis acids used to effect these transformations include SnCU, TMSOTf, TMSCN, Et2AlCN, and HgCN. Additionally, both benzylated and acetylated sugars may be used. 

The anomeric 2,3,4,6-tetra-O-benzoyl-D-glucopyranosyl isocyanides, prepared from the corresponding j8-D-glucosylamine by formylation and dehydration with phosphorus oxychloride, have been polymerized with nickel chloride to give two helical polymers with opposite screw orientations. ... 

The synthesis works best with benzylated halogeno sugars 390 and provides a mixture of anomeric (a + p) isocyanides 391. The isocyanides can also be synthesized by desulfurization of glycosyl isothiocyanates [128]. 

The Ugi reactions, however, did not show any considerable differences between the anomeric glucosyl isocyanides and 2-isocyanoglucose. No higher reactivity was observed. Reactions times were still slow and yields continued to be low. 

Although the reaction conditions did not yield optimal results, Ziegler did show that it was possible to achieve complex glycopeptide derivatives using anomeric glycosyl isocyanides or isocyanoglucoses. 

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