The present invention provides a method of preparing a furan derivative comprising the steps of (a) converting a monosaccharide to provide a keto-intermediate product; and (b) dehydrating the keto-intermediate product to provide a furan derivative; wherein the keto- intermediate product is pre-disposed to forming keto-furanose tautomers in solution. The method may further comprising a step of oxidizing the furan derivative to provide a furandicarboxylic acid or a furandicarboxylic acid derivative.