Lithium Hexamethyldisilazide → 1-Cyclopropanesulfonyl-4,5,7-trifluoro-3-(2-fluoro-4-iodo-phenyl)-1,3-dihydro-benzimidazol-2-one

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Reaction Steps

A stirred solution of 4,6,7-trifluoro-1-(2-fluoro-4-iodo-phenyl)-1,3,-dihydrobenzimidazol-2-one (0.2 gm, 0.41 mmol) in dry THF (4 ml) under nitrogen was cooled to −78° C. and a solution of 1.0 M LiHMDS (0.41 ml, 0.41 mmol) was added slowly. (2 ml) followed by addition of cyclopropanesulfonyl chloride (0.050 ml, 0.49 mmol). This reaction mixture was kept stirring at room temperature for 16 hours, concentrated to dryness and was taken into EtOAc. The EtOAc was washed with water, dried over sodium sulfate and concentrated to dryness. The residue obtained 1-cyclopropanesulfonyl-4,5,7-trifluoro-3-(2-fluoro-4-iodo-phenyl)-1,3-dihydro-benzimidazol-2-one 5 was taken into dioxane (2 ml) and to this 1.0N NaOH (0.5 ml) was added and kept stirring at room 50° C. for 16 hours. TLC indicated incomplete reaction, the product was purified by HPLC to provide off-white solid (4.4 mg) M+H+: 484.7, M−H+: 486.7. 1H NMR (CDCl3, 300 MHZ): 0.9-1.1-(m, 2H); 1.1-1.2 (m, 2H); 2.45-2.55 (m, 1H); 6.05 (s, 1H); 6.44-6.54 (m, 1H); 7.1 (s, 1H); 7.4-7.7 (d, 1H); 7.38-7.44 (dd, 1H); m/z=485 [M−1]−.

Provenance & Evidence