Zemplén methanolysis or a three-step protocol comprising hydroxylaminolysis, de-O- acetylation and deoximination smoothly and efficiently convert the benzoylated 2-hydroxy-d- glycals of d-galactose, l-rhamnose and d-xylose into their configurationally related 1, 5- anhydro-ketoses, thereby providing convenient access to the 1, 5-anhydro forms of d- tagatose, l-rhamnulose and d-xylulose. Invariably obtained as amorphous solids, they are ...