Synthetic approaches to carbohydrate-based ureas

The last decade has witnessed an increasing interest in sugar urea derivatives because of their biological properties. Consequently, new synthetic procedures that explore reactivity differences of the sugar units for the synthesis of molecules bearing urea moiety linked to sugars architecture, have been investigated. The main routes involve isocyanate species, also obtained from the oxidation of isocyanides, by direct reaction with amines or aminosugars or more recently by aza-Wittig reaction with sugar-derived phosphinimines. Other important strategies are based on the reaction of sugar-derived oxazolidinones and carbamates with amines, and modified Curtius rearrangement of sugar carboxylic acids or reaction of sugar-derived phosphinimines with carbon dioxide and amines. This review provides a comprehensive survey of synthetic approach to carbohydrate-based ureas with a focus on the recent procedures.