The transformation of (5R)-2,6-di-O-benzyl-5-C-methoxy-beta-D-galactopyranosyl-(1 -> 4)-2,3:5,6-di-O-iso-propylidene-aldehydo-D-glucose dimethyl acetal (8) into partially protected derivatives of D-xylo- and L-lyxo-aldohexos-5-ulose has been reported, applying appropriate epimerisation methods to its 3'-O- and 4'-O-protected alcoholic derivatives. (C) 2009 Elsevier Ltd. All rights reserved.