70 ^2H-NMRによるリボスタマイシン生合成の立体化学的研究

概要

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The biosynthesis of ribostamycin 1, an aminocyclitol antibiotic, was studied by ^2H-NMR spectroscopy using labeling experiments with [6,6-^2H_2]- and (6S)-[6-^2H]-D-glucose to elucidate for the first time the formation mechanism of neosamine C as well as the mechanism and the stereochemistry of 2-deoxystreptamine (DOS) formation. The amination mechanism at the C-6 position of D-glucose (more probably of D-glucosamine) was suggested to involve an oxidation step of the C-6 hydroxymethyl group into a formyl group, during which the pro S hydrogen is stereospecifically removed. It was also proved that both hydrogen of the hydroxymethyl group of D-glucose is incorporated intact into the C-2 position of DOS and the formation of 7, an early precursor of DOS, is completely different from that of myo-inosose. A plausible mechanism of the intramolecular cyclization of D-glucose into 7 is suggested by analogy to the dehydroquinate (DHQ) synthesis in the shikimate pathway.
天然有機化合物討論会の論文
1981-09-10