Convergent synthesis of pyrrolidine-based (1→6)- and (1→5)-aza-C-disaccharides

A new entry to (1→6)- and (1→5)-aza-C-disaccharides featuring the pyrrolidine ring as the imino sugar component is described via Wittig condensation of polyhydroxylated 2-formylpyrrolidines with galactopyranose 6-phosphorane and ribofuranose 5-phosphorane, respectively.