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-glucopyranosyl phosphate (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.