A facile access to ureido sugars. Synthesis of urea-bridged β-cyclodextrins

The preparation of a urea-bridged β-cyclodextrin dimer and of a 6-monodeoxy-6-mono[3-(β-d-glucopyranos-2-yl)ureido]-β-cyclodextrin has been developed, using triphosgene as the isocyanation agent in an aqueous two-phase system. Per-O-acetylated β-d-gluco and mannopyranosylamines and 2-amino-2-deoxy-α- and β-d-glucose were also transformed into the corresponding isocyanates and converted in situ into ureas by coupling with aromatic and aliphatic amines.