Br[C:2]1[CH:12]=[CH:11][C:5]2[O:6][C:7]([F:10])([F:9])[O:8][C:4]=2[CH:3]=1.C(#N)C.C(N(CC)CC)C>CO.C1C=CC([P]([Pd]([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1>[CH3:5][O:6][C:7]([C:2]1[CH:12]=[CH:11][C:5]2[O:6][C:7]([F:10])([F:9])[O:8][C:4]=2[CH:3]=1)=[O:8]A solution of 5-bromo-2,2-difluoro-benzo[1,3]dioxole (11.8 g, 50.0 mmol) and tetrakis(triphenylphosphine)palladium (0) [Pd(PPh3)4, 5.78 g, 5.00 mmol] in methanol (20 mL) containing acetonitrile (30 mL) and triethylamine (10 mL) was stirred under a carbon monoxide atmosphere (55 PSI) at 75° C. (oil bath temperature) for 15 hours. The cooled reaction mixture was filtered and the filtrate was evaporated to dryness. The residue was purified by silica gel column chromatography to give crude 2,2-difluoro-benzo[1,3]dioxole-5-carboxylic acid methyl ester (11.5 g), which was used directly in the next step.
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