Fortimicins A and B, new aminoglycoside antibiotics. III. Structural identification.

Abstract
The structures of fortimicins A and B were determined by PMR, CMR [carbon magnetic resonance], mass spectra and CD [circular dichroism] combined with chemical degradations. Both antibiotics are pseudodisaccharides and incorporate a novel aminocyclitol, fortamine. In contrast to the diaminocyclitol moieties of known aminglycosides, fortamine is a 1,4-diamine, contains N- and O-methyl groups and possesses chiro stereochemistry. Both antibiotics are glycosides of 6-epi-purpurosamine B, but fortimicin A differs from fortimicin B by being a glycyl amide.