Mass spectra of partially n-acetylated derivatives of kanamycin a

As part of a program concerned with the chemistry and biochemistry of aminocyclitol antibiotics, a number of selectively N-acetylated kanamycins have been prepared from kanamycin monosulfate and characterized by a study of the electron impact induced fragmentation of two types of derivatives. In one of these, the remaining free amino groups were N-trideuteroacetylated and the N-acylated kanamycins thus obtained, were N.O-methylated. The spectra of these derivatives were useful for the location of the N-acetyl and N-trideu-teroacetyl groups, except in the 2-deoxystreptamine unit. In a second type of derivative, the partially N-acetylated kanamycins were N.O-permethylated converting the free amino groups into dimethylamino groups. In this form, it was possible to locate the site of N-aeelylation on the 2-deoxystreptamine ring. The partially N-acetylated kanamycins have been identified as 1,3,6'-tri-N-acetyl, 3,6',3'-tri-N-acetyl, 3,6'-di-N-acetyl, 1,6'-di-N-acetyl and 6'-N-acetyl kanamycin, from a study of the mass spectra of these two types of derivatives.