α-L-Xylofuranuronic acid, 1,2-O-(1-Methylethylidene)-

114861-22-2

1103738-17-5

(3aS,5S,6R,6aS)-5-(Hydroxymethyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol (25.0 g, 131 mmol) was used as a raw material and dissolved in a solvent mixture of acetone (375 mL) and H2O (125 mL). NaHCO3 (33.0 g, 3.0 equiv), NaBr (2.8 g, 20 mol%) and TEMPO (0.40 g, 2 mol%) were added sequentially. The reaction mixture was cooled to 0-5 °C and subsequently trichloroisocyanuric acid (TCCA, 30.5 g, 1.0 eq.) was added in batches. The reaction mixture was stirred continuously at 20 °C for 24 hours. Upon completion of the reaction, methanol (20 mL) was added and stirring was continued at 20 °C for 1 h. At this time, the formation of a white suspension was observed. The solids were separated by filtration and the filter cake was washed with acetone (50 mL). The filtrate was concentrated under reduced pressure to remove the organic solvent and the aqueous layer was extracted three times with EtOAc (300 mL). The organic layers were combined and concentrated to give an oily mixture containing a small solid residue. Acetone (125 mL) was added to the mixture and the acetone solution was concentrated by filtration to give the final target product (3aS,5R,6S,6aS)-6-hydroxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxole-5-carboxylic acid as a yellow solid (21.0 g, 79% yield). The product was confirmed by 1H NMR (methanol-d4), δ 6.00 (d, J = 3.2 Hz, 1H), 4.72 (d, J = 3.2 Hz, 1H), 4.53 (d, J = 3.2 Hz, 1H), 4.38 (d, J = 3.2 Hz, 1H), 1.44 (s, 3H), 1.32 (s, 3H).