Synthesis of glycosyl(thio)ureido sugars via carbodiimides and their conformational behaviour in water
作者:Victor Manuel Dı́az Pérez、Carmen Ortiz Mellet*、José Fuentes、José Manuel Garcı́a Fernández*
DOI:10.1016/s0008-6215(00)00040-9
日期:2000.6
The preparation of sugar ureas and thioureas by nucleophilic addition of water or hydrogen sulfide, respectively, to sugar-derived carbodiimides has been examined. Acetic acid efficiently catalysed the formation of ureas, whereas silica gel was found to be a more convenient catalyst in the case of the thioxo analogues. The procedures have been exploited in the development of an amine- and isocyanate-free synthesis of urea- and thiourea-tethered pseudooligosaccharides via the corresponding glycosylcarbodiimido sugars. The fully unprotected compounds adopted, preferentially, the (Z,Z) configuration at the pseudoamide bonds in water solution.