N,N-Dimethylbenzamide → 4'-(Trifluoromethyl)-[1,1'-biphenyl]-2-carbonyl chloride

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Alternative A. 4′-(Trifluoromethyl)[1,1′-biphenyl]-2-carboxylic acid (133 g), commercially available, thionyl chloride (89 g) and a catalytic amount of N,N-dimethylbenzamide (2.3 g) were combined in toluene (665 mL) at 55-60° C. over 2 hours, and the mixture heated at 80° C. for 1 hour. The excess reagent was removed by atmospheric co-distillation with toluene (600 ml distillate removed), providing a solution of 4′-(trifluoromethyl)[1,1′-biphenyl]-2-carbonyl chloride, which was combined with ethyl 5-amino-1-methyl-1H-indole-2-carboxylate (109 g) from the previous step, ethyl acetate (4660 ml) and N,N-diisopropylethylamine (131 mL) at 18-29° C. The resulting slurry was cooled, filtered and the crude product solids were washed with propan-2-ol (330 mL). The crude product was twice reslurried in a 70/30 mixture of demineralized water and propan-2-ol (2×1500 mL), and the solids were filtered, washed with propan-2-ol (400 mL) and dried, yielding the title compound, ethyl 1-methyl-5-[4′-(trifluoromethyl)[1,1′-biphenyl]-2-carboxamido]-1H-indole-2-carboxylate (167 g, 71.8%).

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