N-bromobutanimide → HCID 178497004, Verbindung

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

7-Fluoro-6-o-tolylamino-1H-benzoimidazole-5-carboxylic acid methyl ester 7a (2.00 g, 6.68 mmol) is suspended in 1:1 THF/MeOH (60 mL) and cooled to −78° C. under a nitrogen atmosphere. A solution of NBS (1.20 g, 6.75 mmol) in 1:1 THF/MeOH (5 mL) is added followed by a MeOH (5 mL) solution of TsOH.H2O (1.9 g, 10.0 mmol). After 30 minutes, the reaction mixture is warmed to 0° C. and then after 1 hour warmed to room temperature. After 16 hours, more NBS (0.12 g, 0.67 mmol) is added and the reaction mixture is allowed to stir for 3 hours. The reaction mixture is quenched by the addition of 10% Na2S2O4 solution. After 30 minutes, the reaction mixture is diluted with water and ethyl acetate and the layers separated. The aqueous layer is extracted with ethyl acetate. The combined organic extracts are dried (Na2SO4) and concentrated under reduced pressure. The recovered solid is triturated with methylene chloride to give 2.00 g (79%) pure desired product: MS APCI (+) m/z 380, 378 (M+1 Br pattern) detected.

Herkunft & Nachweise