Hydrochloric Acid → 2-isopropenylthieno[2,3-b][1,5]benzoxazepin-4(5H)-one

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Reaction Steps

2-Acetylthieno[2,3-b][1,5]benzoxazepin-4(5H)-one (1.8 g) was suspended in ether (15 ml) and 20 equivalent amounts of magnesium methyl iodide was added under ice-cooling. The mixture was stirred at room temperature for 24 hours. The reaction mixture was poured into 1M hydrochloric acid under ice-cooling and insoluble matter was filtered off. The resulting mixture was extracted twice with chloroform. The chloroform layer was dried over sodium sulfate and the solvent was evaporated under reduced pressure. The residue was suspended in toluene and a catalytic amount of p-toluenesulfonic acid was added. The mixture was stirred under reflux with heating for 20 minutes. The reaction system was cooled to room temperature and the reaction mixture was washed with saturated aqueous sodium hydrogencarbonate solution. The solvent was evaporated under reduced pressure and diisopropyl ether was added to the residue. The precipitated crystals were collected by filtration to give 2-isopropenylthieno[2,3-b][1,5]benzoxazepin-4(5H)-one (800 mg).

Provenance & Evidence