Synthesis of N-(2,4-dinitrophenyl) derivatives of D-ribosylamines; unexpected reaction and hydrolysis products

Reaction of 2,3-O-isopropylidene-d-ribofuranosylamine with 2,4-dinitrofluorobenzene afforded the crystalline 2,3-O-isopropylidene-N-(2,4-dinitrophenyl)-β-d-ribofuranosylamine (3) and a 1:1 crystalline complex of 2,3-O-isopropylidene-N-(2,4-dinitrophenyl-α-d-ribofuranosylamine and 2,3-O-isopropylidene-β-d-ribofuranose; controlled acidic hydrolysis of 3 afforded N-(2,4-dinitrophenyl-α-d-ribopyranosylamine and not the expected β-d-furanosylamine derivative. The structures of the new compounds were confirmed by NMR spectroscopy and X-ray crystallography.