1-(2,2-Difluoro-benzo[1,3]dioxol-5-yl)-cyclopropanecarboxylicacid

1-(2,2-Difluorobenzo[1,3]dioxol-5-yl)cyclopropanecarboxylic Acid is used in processes for preparation of Tezacaftor and intermediates thereof.

Compound 21 was hydrolyzed with 6 M NaOH (8 eq.) in ethanol (5 v/v) at 80C. The mixture was cooled to room temperature during the night and the ethanol was evaporated under vacuum. The residue was put into water, MTBE, 1 M HCl was added and the layers were separated. The MTBE layer was then treated with dicyclohexylamine (0.97 eq.). The slurry was cooled to 0C., filtered and washed with heptane to obtain the corresponding DCHA salt. The salts were placed in MTBE and 10% citric acid and stirred until all solids were dissolved. The layers were separated and the MTBE layer was washed with water and brine. After drying in a vacuum oven at 50C, the solvent was exchanged to heptane and then filtered to give compound 1-(2,2-difluorobenzo[D][1,3]dioxol-5-yl)cyclopropanecarboxylic acid. Yield 69%.