Synthesis of α- and β-D-glucopyranuronate 1-phosphate and α-D-glucopyranuronate 1-fluoride: intermediates in the synthesis of D-glucuronic acid from starch

The title uronates were prepared by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) catalysed sodium hypochlorite oxidation of α- and β-D-glucopyranosylphosphate (α-/β-Glc-1-P) and α-D-glucopyranosyl fluoride (α-Glc-1-F). Quantitative recovery of the TEMPO catalyst was achieved by azeotropic distillation of a small part of the reaction mixture. Also, a heterogeneous catalyst system was prepared by immobilisation of 4-oxo-tetramethyl-1-piperidinyloxy (OTEMPO) on amino-functionalized silica. The protected uronates were hydrolysed to yield D-glucuronate. Since α- and β-Glc-1-P and α-Glc-1-F can be obtained from starch in one step, D-glucuronic acid is now available from starch in a convenient three-step sequence.