Synthesis of 6,6′-ether linked disaccharides from D-allose, D-galactose, D-glucose and D-mannose; evidence on the structure of coyolosa

6,6′-Linked ethers derived from D-allose, D-galactose, D-glucose, and D-mannose have been prepared in order to allow comparisons with the reported 6,6′-linked hexopyranose coyolosa, an hypoglycemic compound which has been isolated by extraction of the root of the palm Acrocomia mexicana. Comparison of NMR data from the ethers and their derived peracetates with corresponding reported data from coyolosa and its peracetate indicate that coyolosa is not a 6,6′-linked disaccharide. The synthesised compounds are representatives of a novel class of disaccharide derivatives which are linked tail to tail in contrast to the more usual head to tail (e.g. maltose) or head to head (e.g. trehalose) disaccharides.