Bis-benzyl protected 6-amino cyclitols are poisonous to Pd/C catalysed hydrogenolysis of benzyl ethers

Pd/C and Pd(OH)2/C catalysts are both poisoned by bis-benzyl protected 6-aminocyclitols thereby inhibiting the hydrogenolysis of benzyl ethers but removing N-Cbz groups chemoselectively. This outcome was unaltered by the use of different hydrogen donors. Replacement of the C-6 nitrogen atom by oxygen resulted in the starting materials being fully deprotected under similar conditions. These findings add cyclitolamines to the list of amines/bases that are poisonous to Pd/C catalysts during hydrogenolysis.