2-Bromoethanol → 2,3-Benzofurandione, 2-[O-(2-hydroxyethyl)oxime] 3-(O-methyloxime)

Participants

Reaction Steps

4.49 g (0.0234 mol) of benzofuran-2,3-dione 3-(O-methyl-oxime) 2-oxime (VIII-1) are dissolved in 25 ml of dimethylformamide. 1 g (0.025 mol) of 60% strength sodium hydride is added to this solution which is then stirred at room temperature for one hour. 3.1 g (0.0248 mol) of 2-bromoethanol are added and the mixture is stirred at 25° C. for 12 hours. After the addition of 0.5 g of sodium methoxide and 1.22 g of 2-bromoethanol, the mixture is stirred at room temperature for 2 hours. A further 0.5 g of sodium methoxide and 1.22 g of 2-bromoethanol are added and the mixture is stirred for a further 2 hours at room temperature. The reaction mixture is poured into water and the resulting mixture is extracted with ethyl acetate and the organic phase is washed 3 times with 20 ml of 2 N aqueous sodium hydroxide solution. The solvent is distilled off under reduced pressure and the residue is chromatographed over silica gel using diethyl ether/petroleum ether (1:1). The eluent is distilled off under reduced pressure, affording 2.26 g (39.6% of theory) of benzofuran-2,3-dione 2-[O-(2-hydroxy-ethyl)-oxime] 3-(O-methyl-oxime) (II-1) which, according to HPLC, comprises 84.29% of stereoisomer A and 12.58% of stereoisomer B.

Provenance & Evidence