Anthranilic amide and imidazobenzothiadiazole compounds disrupt Mycobacterium tuberculosis membrane potential

Compounds 1 and 2 disrupt M. tuberculosis membrane potential and demonstrate bactericidal activity against non-replicating M. tuberculosis in pH 4.5 buffer.


General Methods
Reagents and solvents were purchased from Sigma-Aldrich, Acros Organics, Alfa Aesar, Matrix Scientific, Enamine, or Fisher Scientific and used without further purification. NMR spectra were collected on a 300 MHz Bruker AVANCE 300 system with 5 mm BBI probe. LC-MS was performed on an Agilent 1100 system with Phenomenex Gemini 5 µM C18 column and 0.5% formic acid buffered acetonitrile/water gradient elution. Thionyl chloride (1.89 mL, 26 mmol) was added slowly to a solution of 2-nitrobenzoic acid (3.34 g, 20 mmol) and DMF (2.0 mL, 26 mmol) in DCM (100 mL). The resulting solution was refluxed for 4 h. The reaction mixture was cooled to room temperature and concentrated in vacuo to provide the crude acid chloride which was used without further purification.

N-(2,4-dichlorophenyl)-2-nitrobenzamide (S1)
A solution of the acid chloride prepared above in DCM (100 mL) was added to a solution of 2,4dichloroaniline (4.21 g, 26 mmol) in DCM (100 mL) and pyridine (20 mL). The resulting solution was stirred overnight.The reaction mixture was diluted with 1 M HCl (aq) and the layers separated. The aqueous layer was back-extracted with one portion of EtOAc. The combined organic layers were washed with brine, dried over Na 2 SO 4 , and concentrated in vacuo. The crude material was purified by flash column chromatography on silica gel (24 g) eluting with a gradient from 0-20% EtOAc in hexanes then 100% EtOAc to give 5.45 g (88%) off-white solid.

3-(4-bromophenylsulfonamido)-N-(2,4-dichlorophenyl)benzamide (26)
The resulting solution was refluxed for 4 h. The reaction mixture was cooled to room temperature and concentrated in vacuo to provide the crude acid chloride which was used without further purification.
2,4-dichloroaniline (59 mg, 0.36 mmol) and pyridine (0.28 mL) were added to a solution of the acid chloride prepared above in DCM (2.8 mL). The resulting solution was stirred overnight.The reaction mixture was diluted with DCM washed with 1 M HCl (aq), water, and sat. NaHCO 3 (aq), dried over Na 2 SO 4 , and concentrated in vacuo. The crude material was purified by flash column chromatography on silica gel (4 g) eluting with a gradient from 0-20% EtOAc in hexanes to give 13 mg (9%) off-white solid. Thionyl chloride (0.47 mL, 6.5 mmol) was added slowly to a solution of 2-iodobenzoic acid (1.24 g, 5 mmol) and DMF (0.5 mL, 6.5 mmol) in DCM (25 mL). The resulting solution was refluxed for 4 h. The reaction mixture was cooled to room temperature and concentrated in vacuo to provide the crude acid chloride which was used without further purification.
A solution of the acid chloride prepared above in DCM (25 mL) was added to a solution of 2,4dichloroaniline (1.05 g, 6.5 mmol) in DCM (25 mL) and pyridine (5 mL). The resulting solution was stirred overnight.The reaction mixture was diluted with 1 M HCl (aq) and the layers separated. The aqueous layer was back-extracted with one portion of EtOAc. The combined organic layers were dried over Na 2 SO 4 and concentrated in vacuo. The crude material was purified by flash column chromatography on silica gel (12 g) eluting with a gradient from 0-20% EtOAc in hexanes to give a mixture of product and 2,4-dichloroaniline which was used without further purification.  (16), [4144][4145][4146][4147]2016), and 1,2-dimethylethylenediamine (2.7 µL, 0.025 mmol) in DMSO (2.5 mL). The resulting mixture was heated to 110°C overnight. LC-MS showed incomplete conversion. Additional sodium 4-bromobenzene-1-sulfinate (31 mg, 0.13 mmol) and cupric iodide (4.8 mg, 0.025 mmol) were added, and the mixture was heated back to 110°C overnight. The reaction mixture was cooled to room temperature, diluted with water, and extracted with two portions of EtOAc. The combined organic layers were washed with 1 M HCl (aq), sat. NaHCO 3 (aq), and two portions of brine, dried over Na 2 SO 4 , and concentrated in vacuo. The crude material was purified by flash column concentration on silica gel (12 g) eluting first with hexanes then a gradient from 0-25% EtOAc in hexanes to give 160 mg purple-white solid which was pure by LC-MS.