Study of the m/z [H-1(2)+13](+) ion in 2-aminopyranoside derivatives

The electron impact spectra of 2-N-alkyl, 2-N-acyl-2-N-alkyl and 2-N,N-dial kyl aminosugar derivatives, as well as 2- aminosugar derivatives themselves , all show an [H-1(2) + 13](+) ion.(b) In previous work, it was considered that this ion was derived from the [M - OR1](+) ion and was designated as [ M - OR1 - 178](+), In the present work, the structure and origin of the [H- 1(2) + 13](+) ion is studied in detail, and it is demonstrated that it orig inates first from the molecular ion, via a primary fragmentation, and secon d from the [M - OR1](+) ion, in both cases by a [3 + 3] cleavage of the pyr anose ring.