Molybdic Acid-Catalyzed Mutual Interconversions of 2-C-(Hydroxymethyl)-D-glucose with D-manno-Hept-2-ulose and 2-C-(Hydroxymethyl)-D-mannose with D-g/uco-Hept-2-ulose

Nitromethane synthesis with D-fructose followed with the Nef reaction of intermediate 1-deoxy2-C-hydroxymethylhexitol-l-nitronates afforded 2-C(hydroxymethyl)-D-glucose and -D-mannose which were separated via their phenylhydrazones and by chromatography on a cation-exchange resin in the B a 2 + form. The treatment of individual branched-chain aldoses with catalytic amount of molybdic acid, i.e. under the conditions of the Bilik reaction afforded thermodynamic equilibrium mixtures of 2-č^(hydroxymethyl)-D-ghicose and D-manno-hept-2-ulose in the mole ratio 2 55 and of 2-C(hydroxymethyl)-D-mannose and D-ýíitco-hept-2-ulose in the ratio 2 23, respectively. The same equilibria were obtained also from the side of hept-2-uloses. Due to easy availability of 2C-(hydroxymethyl)-D-mannose also from its di-O-isopropylidene derivative the interconversion was advantageously used for one-step synthesis of D-phzco-hept-2-ulose.