反应详情

R4K was characterized as a free base and consisted, according to HPLC, of essentially one product, the kanamycin A derivative. The 1H NMR (400 MHz, D2O) spectrum revealed the presence of the characteristic groups of the protons of arginine amide moieties at chemical shifts of (δ) 3.38 (Hα), 3.21 (Hβ) and 1.64 ppm (Hγ,δ) All the characteristic kanamycin proton signals, in particular the anomeric hydrogens (as doublets at 4.99 and 5.15 ppm), were observed. Integration afforded 1:4 ratio of antibiotic to arginine components. A 13C NMR (100,609 MHz 10% D2O) spectrum of R4K revealed carbon resonances of the C-arginine amide moieties and the kanamycin moiety. The presence of antibiotic anomeric carbon signals at δ 101.77 and 101.07 ppm, the amide carbons at 181.13, 180.81, 180.38, 179.76 ppm and the guanidino carbons at 159.47 ppm 5 confirmed the structure of the aminoglycoside-arginine conjugate. FABHRMS of R4K revealed a mass peak of 1109.7 Da (calculated molecular weight of R4K: 1109.25 Da). A second peak of 1067.4 Da (−42.3 from mass peak) was attributed to a loss of aminoamino carbon fragment during ionization.