Dimethylformamide → 2',6'-Dimethyl-1,1'-biphenyl-4-carboxylic acid chloride

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Reaction Steps

A stirred solution of 2′,6′-dimethyl-1,1′-biphenyl-4-carboxylic acid of Step A (0.790 g, 3.5 mmol) in dichloromethane (15 mL) was treated under nitrogen with a catalytic amount of N,N-dimethylformamide followed by dropwise addition of 2N oxalyl chloride in dichloromethane (2.8 mL). After the gas evolution ceased the mixture was refluxed for 4 hours, cooled, and evaporated. The residue was azeotroped twice with benzene and dried in vacuo to provide 2′,6′-dimethyl-1,1′-biphenyl-4-carboxylic acid chloride. The crude 2′,6′-dimethyl-1,1′-biphenyl-4-carboxylic acid chloride (0.856 g, 3.5 mmol) was dissolved in dichloromethane (7 mL) and added dropwise to a suspension of N-(pyridin-3-ylmethyl)-10,11-dihydro-5H-pyrrolo[2,1-c][1,4]benzodiazepine-3-carboxamide of Example 12 (0.450 g, 1.41 mmol) in anhydrous tetrahydrofuran 10 mL) containing N,N-diisopropylethyl amine (0.860 mL). The mixture was stirred for 18 hours at room temperature and evaporated to dryness. The residue was dissolved in dichloromethane, the solution washed with saturated aqueous sodium bicarbonate and brine, dried over anhydrous potassium carbonate and evaporated. The residue was chromatographed over silica gel Merck-60 eluting with a gradient from 0 to 4% methanol in 1:1 hexane-ethyl acetate to provide the title compound (0.452 g) as a white solid after trituration with hexane, m.p. 216-218° C. (dec).

Provenance & Evidence