NHC-catalysed synthesis of hydroxy methylene-bridged formyl-di-xylofuranose: access to tetrakis and spiro tricyclic xylofuranose

Herein, the role of <i>N</i>-heterocyclic carbenes (NHC) as a Brønsted base in the transformation of xylofuranose aldehyde has been explored. Furanose aldehyde undergoes intermolecular self-condensation catalyzed by thiazolium-derived carbene, producing hydroxy methylene-bridged formyl-di-xylofuranose retaining the C-4 aldehyde. Furthermore, modification of the hydroxy methylene-linked disaccharide yields spiro[furano-4,5-pyrano[3,2-<i>b</i>]furanose] and oxy-methylene-bridged di-formyl-xylofuranose cyclic tetrasaccharide.