FC(F)(F)C(O)=O.[CH3:8][C:9]1([CH3:27])[O:13][C:12]2[CH:14]=[CH:15][C:16]([F:26])=[C:17]([NH:18]C(=O)OC(C)(C)C)[C:11]=2[O:10]1.C(OCC)C.C(=O)(O)[O-].[Na+]>O>[NH2:18][C:17]1[C:11]2[O:10][C:9]([CH3:8])([CH3:27])[O:13][C:12]=2[CH:14]=[CH:15][C:16]=1[F:26]
In a flask was placed 50 mL of trifluoroacetic acid which was cooled to 0° C. To this cooled trifluoroacetic acid was added 11.5 g (0.041 mole) of t-butyl N-(2,2-dimethyl-5-fluoro-1,3-benzodioxol-4-yl)carbamate. This mixture was allowed to warm to ambient temperature at which it was stirred for 90 minutes. Diethyl ether and water were added to the mixture which was made basic with sodium bicarbonate. The organic phase was separated from the aqueous phase, and the former was dried with anhydrous magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure, and the residue was passed through a column of silica gel, eluting with methylene chloride/heptane (1:1). Product-containing fractions were combined and the solvent evaporated under reduced pressure, yielding 4.9 g of 4-amino-2,2-dimethyl-5-fluoro-1,3-benzodioxole as the residue. The NMR spectrum was consistent with the proposed structure.
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