Citric Acid → N-Butyloxycarbonyl-3-(3-benzoimidazol-1-ylmethylphenyl)-5-iso-butylthio-phene-2-sulfonamide

Participants

Reaction Steps

To a solution of 3-(3-benzoimidazol-1-ylmethylphenyl)-5-iso-butyl-N-tert-butylthiophene-2-sulfonamide (67.6 mg, 0.14 mmol; see step (a)) in CH2Cl2 (2 mL) was added BCl3 (0.6 mL, 1.0 M in hexane) and the reaction mixture was stirred for 1 h at ambient temperature. The reaction mixture was concentrated in vacuo. Water (5 mL) was added to the residue and this was then extracted with EtOAc. The combined organic phase was washed with water and brine, dried (over anhydrous MgSO4) and concentrated in vacuo. To the crude product dissolved in pyridine (1.5 mL) was added pyrrolidinopyridine (41.6 mg, 0.28 mmol) and butyl chloroformate (178.4 μL, 1.40 mmol) and the reaction mixture was stirred overnight. Citric acid (3 mL, 10% aq.) was added to the reaction mixture, which was then extracted with EtOAc, dried (over anhydrous MgSO4), concentrated in vacuo, and the residue purified by flash chromatography using MeOH:CH2Cl2 (5:95) as eluent to give the title compound in 70% yield, over two steps, (51.6 mg, 0.098 mmol).

Provenance & Evidence