tert-Butyl (2-(2,2-dimethyl-4H-benzo[d][1,3]dioxin-6-yl)-2-oxoethyl)carbamate

Tert-Butyl (2-(2,2-dimethyl-4H-benzo[d][1,3]dioxin-6-yl)-2-oxoethyl)carbamate is a Vilanterol impurity. Vilanterol is a novel and selective agonist of β2-ar.

Trifluoroacetic acid (10.2 mL) was added to di-(tert-butyl)2-(2,2-dimethyl-4H-1,3-benzodioxin-6-yl) -2-oxoethyliminodicarbonic acid at 20°C (46.37 g) in a stirred solution of dichloromethane (500 mL) and stirred for 4 hours. Aqueous sodium hydroxide solution (0.5 M, 400 mL) was added to the reaction solution, stirred for half an hour, and separated. The organic layer was washed with water (500 mL), dried, concentrated, and recrystallized from ether to obtain tert-Butyl (2-(2,2-dimethyl-4H-benzo[d][1,3]dioxin-6-yl)-2-oxoethyl)carbamate 15.15g, yield 43 %.