A short synthesis of p-nitrophenyl α-d-xylofuranoside and β-d-arabinofuranoside employing a Mitsunobu glycosylation

Chromogenic p-nitrophenyl glycosides are widely used substrates for glycosidase assays, yet analogous derivatives of rare pentofuranoses remain largely unavailable. We report concise five-step syntheses of p-nitrophenyl β-d-arabinofuranoside and p-nitrophenyl α-d-xylofuranoside using a Mitsunobu glycosylation between the corresponding sugar hemiacetals and p-nitrophenol. The use of benzyl-protected donors simplifies preparation of the furanosyl donors, and mild oxidative debenzylation (KBrO₃/Na₂S₂O₄) preserves the nitro group. Both glycosides were obtained in good overall yield, and their structures, including anomeric configurations, were confirmed by single-crystal X-ray diffraction. This route furnishes practical access to these useful chromogenic furanosides, which will facilitate biochemical and mechanistic studies of α-d-xylofuranosidases, β-d-arabinofuranosidases, and related enzymes of pentofuranoside metabolism.