Fast and effective reduction of nitroarenes by sodium dithionite under PTC conditions: application in solid-phase synthesis

Herein, conditions for the fast and effective reduction of aromatic nitro groups bound to hydrophobic polystyrene-based Wang and Ring resins utilizing sodium dithionite in dichloromethane–water under PTC conditions are reported. Tetrabutylammonium hydrogen sulfate (TBAHS) was found to be an effective phase-transfer catalyst for this reaction. This method allows for the reduction of nitro groups to amino groups under mild conditions with complete conversion and is tolerant of other functional groups. This method is a superior alternative to tin(II) chloride-based reduction, which is known for its shortcomings.