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-GLUCO-HEPT-2-ULOSE

Nitromethane synthesis with D-fructose followed with the Nef reaction of intermediate 1-deoxy-2-C-hydroxymethylhexitol-1-nitronates afforded 2-C-(hydroxymethyl)-D-glucose and -D-mannose which were separated via their phenylhydrazones and by chromatography on a cation-exchange res in in the Ba2+ form. The treatment of individual branched-chain aldose s with catalytic amount of molybdic acid, i.e. under the conditions of the Bilik reaction afforded thermodynamic equilibrium mixtures of 2-C -(hydroxymethyl)-D-glucose and D-manno-hept-2-ulose in the mole ratio 2 : 55 and of 2-C-(hydroxymethyl)-D-mannose and D-gluco-hept-2-ulose i n the ratio 2 : 23, respectively. The same equilibria were obtained al so from the side of hept-2-uloses. Due to easy availability of 2-C-(hy droxymethyl)-D-mannose also from its di-O-isopropylidene derivative th e interconversion was advantageously used for one-step synthesis of D- gluco-hept-2-ulose.