R~:action of azido sugars with triphenylphosphine affords sugar phosphinimines [1,2], that are good precursors [3][4][5] for various nitrogen derivatives of sugars. In order to obtain aJ-amino sugar l'ormazan derivatives, the reduction of 6-azido-O-deoxy-o-galac-tos¢ N,N'-diphenylformazan [6] (1) was carried out with triphenylphosphine. The reaction took place in dioxane or 1,2-dimethoxyethane containing methanol, moreover best in 2-methoxyethanol, and aflbrded a red formazan compound (4) as main product. Acetylation of this latter with pyridine~-acetic anhydride gave an N-acetyl.tri-O-acetyiderivative ($).
On the basis of their visible, IR, ~H and ~3C NMR spectra these compounds proved to be 2,6-dideoxy-2,6-imino-D-talose N,N'-diphenylformazan (4) and its tetraacetyl derivative (5) instead of the expected 6-deoxy-6-phosphinimino-(2) or 6-amino-6-deoxy-(3) compounds and their acetates. The presence of the formazan chelate was supported by maxima at 458 nm for 4 and 464 nm for $, respectively, in the visible spectra.