Equilibria between pyranoses and furanoses. IV. 1-Deoxyhexuloses and 3-hexuloses.

The equilibrium compositions of 1-deoxy-D-fructose, 1-deoxy-L-sorbose, 1-deoxy-L-psicose, D-threopentulose, D-arabino- and L-xylo-3-hexulose and coriose in aqueous solution have been determined by 13C N.M.R. spectroscopy. In all but the last case, considerable amounts of the acyclic keto form are present at equilibrium. The hydrated keto form was not detected; a model compound, l-deoxy- 3,4,5,6-tetra-O-methyl-D-fructose, was found not to be hydrated in aqueous solution.