A Short Enzymatic Synthesis of L-Glucose from Dihydroxyacetone Phosphate and L-Glyceraldehyde

摘要

Unnatural monosaccharides are potentially useful as nonmetabolizable sweeteners and as building blocks for the synthesis of interesting natural and biologically active products. L-Glucose 1 and L-fructose 2, for example, are known to be low-calorie sweeteners. Compound 2 was previously prepared by enzyme-catalyzed aldol addition reaction, selective cross-acy-loin condensation from tetra-O-acetyl-L-arabinose and formaldehyde, L-mannose isomerization catalyzed by cell-free extracts of Aerobacter aerogenes, bacterial oxidation of L-mannitol, and chemical synthesis from L-sorbose. 1 was previously prepared via a multichemical transformation from D-glucose (12.7%, 8 steps, 326 μmol) or L-arabmose, via asymmetric epoxidation of (E)-2-butenediol (2.6%, 9steps, 64 μmol), via asymmetric Diels-Alder reaction (4.5%, 9 steps, 44 μmol), and via chemoenzymatic synthesis from commercially available cycloheptatriene (8.9%, 21 steps, 523 μmol). Compound 1 was also prepared by galactose oxidase-catalyzed stereospecific oxidation of L-glucitol (10--15%, 180 μmol) and by transketolase-catalyzed reaction with L-arabi-nose.