N-(4-amino-2-fluorophenyl)methanesulfonamide → 8-Tert-butyl-1-oxa-2-azaspiro[4.5]dec-2-ene-3-carboxylic acid-(3-fluoro-4-methanesulphonylaminophenyl)amide

Participants

Reaction Steps

The acid 8-tert-butyl-1-oxa-2-azaspiro[4.5]dec-2-ene-3-carboxylic acid (359 mg, 1.5 mmol) was dissolved in THF (15 ml). N,N′-carbonyldiimidazole (243.5 mg, 1.5 mmol) was added while stirring. For activation, the mixture was stirred for 1 h at RT. The N-(4-amino-2-fluorophenyl)methanesulphonamide (326.8 mg, 1.60 mmol) was then added as a solid. The course of the reaction was controlled by DC. After 3 d only small amounts of starting products could still be seen in the DC. For working up, THF was removed by distillation. The residue was dissolved in 0.5 N aq. HCl (10 ml) and EtOAc (40 ml). The phases were separated. The organic phase was washed successively with 0.5 N aq. HCl (2×8 ml), with water (1×10 ml), with 1.1 M aq. NaHCO3 solution (3×7 ml) and water (3×10 ml). The organic phase was dried with Na2SO4. The solvent was removed by distillation. The light brown residue was stirred out with diethyl ether (3×2 ml). The solvent was in each case removed by suction-filtration. The light pink residue was the mixture of the diastereoisomers of 8-tert-butyl-1-oxa-2-azaspiro[4.5]dec-2-ene-3-carboxylic acid-(3-fluoro-4-methanesulphonylaminophenyl)amide (353 mg, mp 104-107° C. and 228-232° C., 55%).

Provenance & Evidence