Synthesis and chromatographic properties of isomeric O-β-d-galactopyranosyl-d-galactoses, and of diastereo-isomers of 3,4-O- and 4,6-O-(1-carboxyethylidene)-d-galactose

Partial hydrolysis of β-d-galactopyranans and d-galactose-containing polysaccharides having pyruvic acetal groups gives isomeric O-β-d-galactopyranosyl-d-galactoses and O-(1-carboxyethylidene)-d-galactoses, respectively. Their chromatographic properties in various systems were investigated as an aid in identification. The best method was a combination of silica gel t.l.c., which separates the 3,4- and 4,6-O-(1-carboxyethylidene) derivatives, and paper electrophoresis in borate buffer, which resolves the 2-O-, 3-O-, 4-O-, and 6-O-linked galactobioses after removal of the O-(1-carboxyethylidene) derivatives. 2-O- and 4-O-β-d-Galactopyranosyl-d-galactoses were synthesized, as well as the 4 diastereoisomeric 3,4- and 4,6-O-(1-carboxyethylidene)-d-galactoses.