Phosphorus oxychloride → 2-(5-bromopyridine-3-yl)-1-phenyl-1H-benzimidazole

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Reaction Conditions

Reaction Steps

Compound 1E (20.0 g, 54.3 mmol) was dissolved in 1,4-dioxane (anhydrous, 150 mL). Phosphorous oxychloride (36 g, 235 mmol) was then added dropwise. The resulting solution was heated at about 100° C. overnight; solids formed. After cooling to RT, the mixture was poured into hexanes (250 mL) to form additional precipitate. Solids were filtered then redissolved in DCM (200 mL) and washed with potassium carbonate (200 mL, saturated solution). The organic phase was collected, dried over sodium sulfate, and loaded onto silica gel. Short silica plug (20% ethyl acetate in hexanes and precipitation from hexanes gave 16.86 g of Compound 1F; 89% yield, pure by HNMR.

Provenance & Evidence