Oxamicetin, a new antibiotic of bacterial origin. II. Structure of oxamicetin.

General Structural Characteristics Oxamicetin (I) is a basic antibiotic which crystallizes as a hydrochloride hydrate. Elemental analysis and titration data0 were consistent with a molecular formula of C29H42N6O10for the free base, indicating one additional oxygen atom compared to amicetin. Oxamicetin shows strong absorption in the ultraviolet region with, spectra at various pH values0 very similar to those of amicetin2). The IR spectrum0 showed absorptions due to hydroxyl groups (3300cm"1), amide carbonyls (1690, 1640) and conjugated C=C bonds (1600cm"1). Oxamicetin gives positive ninhydrin, Dragendorff and anthrone reactions but is negative to Fehling's and Tollens' reagents, indicating the absence of reactive reducing sugar moieties. The NMRspectrum of oxamicetin hydrochloride in deuterium oxide showed three C-CH3(two doublets centered at d 1.44 and 1.55ppm, one singlet at <H.78ppm) and one dimethylamino group at <53.09ppm0. The à"characteristic two vinyl protons appeared as doublets at d 7.32 (J=7.5Hz) and 8.09ppm (J=7.5Hz) and four aromatic protons as an ABquartet at d 7.58 and 7.80ppm (J=9.0Hz). In addition, two anomeric protons were observed at d 5.32 (doublet, J=3.5Hz) and 5.70ppm (broad doublet, J=10.5 Hz). These NMRdata were also suggestive of the close structural similarity of this antibiotic to -amicetin.