Potassium Carbonate → 6-(4-Bromo-2-chloro-phenylamino)-7-fluoro-3-(tetrahydro-pyran-2-ylmethyl)-3H-benzoimidazole-5-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

6-(4-Bromo-2-chloro-phenylamino)-7-fluoro-3H-benzoimidazole-5-carboxylic acid methyl ester 8b (0.25 g, 0.63 mmol) is dissolved in N,N-dimethylformamide (5 mL). 2-Brothomethyl-tetrahydro-pyran (0.34 g, 1.88 mmol) and potassium carbonate (0.26 g, 1.88 mmol) are added and the reaction mixture is stirred at 60° C. for 12 hours under N2. The reaction mixture is poured into a separatory funnel, diluted with ethyl acetate and water and the layers separated. The ethyl acetate layer is washed with water and brine, dried (Na2SO4) and concentrated under reduced pressure. The resulting solid residue is triturated with diethyl ether to yield a pale yellow solid (N3 regioisomer by NMR) and a yellow filtrate (mixture of N1 and N3 regioisomers by NMR). The solids are collected and washed with diethyl ether to yield 0.12 g (37%) of the pure desired N3 regioisomeric product as a pale yellow solid. MS ESI (+) m/z 496, 498 (M+, Br pattern) detected.

Provenance & Evidence