2,3-dibromo-2,3-dihydro-1,4-benzodioxine

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 73.45 mmol of the compound obtained in Step A above are dissolved in 125 ml of acetone; the solution is then stirred for 2 hours under reflux, in the presence of sodium iodide (359.9 mmol). After evaporating off the solvent, the residue is dissolved in a mixture of water/ethyl acetate (100 ml/200 ml). The organic phase is then washed with 20% aqueous sodium thiosulphate solution and then the aqueous phase is extracted twice with ethyl acetate. The organic phases are combined, dried over magnesium sulphate and then concentrated to dryness. Purification by chromatography over silica gel (petroleum ether/ethyl acetate: 95/5) allows the expected product to be obtained. After evaporating off the solvent the residue is dissolved in a mixture of water/ethyl acetate (100 ml/200 ml) The organic phase is then washed with 20% aqueous sodium thiosulphate solution the aqueous phase is extracted twice with ethyl acetate dried over magnesium sulphate concentrated to dryness Purification by chromatography over silica gel (petroleum ether/ethyl acetate: 95/5) to be obtained