Potassium Formate → 6-(2-Dodecylsulfonylbutyryl)amino-5-fluoro-benzoxazol-2-one

Participants

Reaction Steps

In a 250-ml flask, place 9.9 g (0.05 m) of 5-fluoro-6-nitro-benzoxazol-2-one (2a), 40 ml of isopropyl alcohol and 20 ml of propyl acetate, and 0.4 g 5% Pd/C with 1.5 ml of water. Add 16.8 g (0.2 m) of potassium formate in 20 ml of water, and stir the mixture vigorously at 55°-60° C. for 4 hrs. Keep strictly inert nitrogen atmosphere throughout the reaction. Take a TLC to confirm completeness of reaction. Cool the reaction mixture containing 6-amino-5-fluoro-benzoxazol-2-one (3a, X=F) to 40° C. under nitrogen, and add 40 ml of propyl acetate and a solution of 18.8 g (0.05 m×1.05 @95%) of 2-dodecylsulfonyl-butyryl chloride (R′COZ; R′=1-dodecylsulfonylpropyl and Z=Cl) in 60 ml of propyl acetate keeping the temperature at 40°-45° C. over 15 min. Stir the reaction mixture at 40° C. for 30 min. Add 60 ml of water and filter off catalyst and wash it with 60 ml of propyl acetate and 60 ml of water. Separate propyl acetate solution, wash with 120 ml of 1N HCl, and concentrate under a reduced pressure to a thick slurry. Cool the slurry in an ice-water bath for 2 hrs. Collect solid, wash with chilled propyl acetate and heptane, and dry in a vacuum oven to give 18.6 g (79%) of 6-(2-dodecylsulfonylbutyryl)amino-5-fluoro-benzoxazol-2-one (Formula I, Y=X=F and R′=1-dodecylsulfonylpropyl) as off-white solids.

Provenance & Evidence