SYNTHESIS OF A PROTECTED GLYCOSIDE OF ALPHA-D-PURPUROSAMINE-C BY CYCLOADDITION

The pseudotrisaccharide mixture Gentamicin1, 2 is a broad-spectrum aminoglycoside antibiotic complex, designated as gentamicins C1, C2, and C1a, produced by Micromonospora purpurea. Each pseudotrisaccharide contains the branched-chain amino sugar garosamine, the aglycon 2-deoxystreptamine, and one of three different 2, 6-diamino-2, 3, 4, 6-tetradeoxyaldoses, which have been named purpurosamine A, B, and C from gentamicins C1, C2, and C1a, respectively. The meso-2-deoxystreptamine is asymmetrically-glycosylated in the gentamicins at C-4 with the purpurosamine subunits. The pseudodisaccharide gentamines, 3 which are deprived of the garosamine subunit, exhibit interesting antibacterial activity. Recently, a new type of aminoglycoside antibiotic pseudodisaccharide, the Fortimicins, 4 was isolated, containing only one sugar unit, ept-purpurosamine B. The position and nature of all linkages to the novel aminocyclitol fortamine have been firmly established. Several syntheses of purpurosamine C derivatives have been already reported.5-11. © 1979, American Chemical Society. All rights reserved.