反应详情

A mixture of 0.9 g (4.2 mmol) of ethyl 5-hydroxy-6-aminobenzofuran-2-carboxylate [Helv. Chim. Acta 77, 100. (1994)], 60 ml of tetrahydrofuran, 3.1 ml of 20% phosgene in toluene solution and 2.0 ml of triethylamine is stirred at room temperature for 1 h. The tetrahydrofuran is distilled off in vacuum, water is added to the residue and the product is extracted with ethyl acetate. The combined organic layers are washed with 5% aqueous sodium hydrogencarbonate solution, water, 1 N hydrochloric acid solution and again with water, dried over sodium sulfate and concentrated to yield 1.0 g (96%) of the title compound as oil.

1. distillationThe tetrahydrofuran is distilled off in vacuum, water
2. additionis added to the residue
3. extractionthe product is extracted with ethyl acetate
4. washThe combined organic layers are washed with 5% aqueous sodium hydrogencarbonate solution, water, 1 N hydrochloric acid solution and again with water
5. dry with materialdried over sodium sulfate
6. concentrationconcentrated