One-step synthesis of dibutyl furandicarboxylates from galactaric acid

Dibutyl 2,5-furandicarboxylate (2) and dibutyl 2,3-furandicarboxylate (3) were synthesized using one step from galactaric acid and I-butanol. Sulfuric acid, p-toluenesulfonic acid, and heteropolyacids were good catalysts for the reaction. The reaction time was dependent on the amount of the catalyst, but the final yields of the main product, 2 remained unchanged.