Tetrabutylammonium Fluoride → HCID 68814249, compound

Participants

Reaction Steps

To a solution of 3-benzyl-2-oxo-7-(1-triisopropylsilanyl-1H-pyrrol-3-yl)-2,3-dihydro-benzoimidazole-1-carboxylic acid tert-butyl ester (0.768 g, 1.40 mmol) in 30 ml 1,4-dioxane was added tetrabutylammonium fluoride (1.548 mL of a 1M solution in tetrahydrofuran, 1.548 mmol) dropwise over 5 minutes. The reaction mixture was stirred for 45 minutes, and was then added to 200 mL of 1:1 water/ethyl acetate. The layers were separated and the aqueous layer was extracted twice with 100 mL ethyl acetate. The combined organic fractions were dried over sodium sulfate and concentrated in vacuo and purified by flash chromatography (20 to 40% gradient ethyl acetate in hexanes) to give 0.447 g of crude 3-benzyl-2-oxo-7-(1H-pyrrol-3-yl)-2,3-dihydro-benzoimidazole-1-carboxylic acid tert-butyl ester. This material was dissolved in 7 mL tetrahydrofuran and cooled to 0° C. under nitrogen. To this solution was added di-tert-butyldicarbonate (0.752 g, 3.45 mmol) and 4-dimethylaminopyridine (14 mg, 0.115 mmol) and stirring was continued for one hour as the reaction mixture was allowed to warm to room temperature. The reaction mixture was concentrated in vacuo and the residue was purified by flash chromatography (1 to 10% gradient ethyl acetate in hexanes) to give 0.550 g of 3-benzyl-7-(1-tert-butoxycarbonyl-1H-pyrrol-3-yl)-2-oxo-2,3-dihydro-benzoimidazole-1-carboxylic acid tert-butyl ester, MS: 490 (M+H)+.

Provenance & Evidence