Tributylphosphine → N-tosyl Tegoprazan

Participants

Reaction Steps

To a stirred mixture of 4-hydroxy-N,N,2-trimethyl-1-[(4-methylphenyl)sulfonyl]-1H-benzimidazole-6-carboxamide (21.2 g, 56.8 mmol, STEP 4), (+)-5,7-difluoro-3,4-dihydro-2H-chromen-4-ol (15.86 g, 85.1 mmol, STEP 8) and tributylphosphine (22.9 g, 113 mmol) in toluene (840 mL) was added 1,1′-(azodicarbonyl)dipiperidine (ADDP) (19.3 g, 76.5 mmol) at room temperature. After stirring at room temperature for 2 hours, the reaction mixture was filtered through a pad of Celite and washed with ethyl acetate (300 mL). The filtrate was concentrated in vacuum. The residue was purified by column chromatography on silica get (ethyl acetate:hexane gradient elution from 1:20 to 20:1) to afford crude solids (27.0 g). The solids were recrystallized from 2-propanol (130 mL) to give the title compound as a colorless crystal (23.2 g, 75%, >99% ee)

Provenance & Evidence