butyl 2,3-dibromopropanoate

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: The product (300 g) of Step 1 and p-methoxyphenol (2 g) was added to a 2 l. round bottom flask fitted with a thermometer, condenser, stirrer and inlet for nitrogen, and containing acetonitrile (1000 ml) and anhydrous potassium carbonate (330 g). The reaction mixture was stirred under reflux for 8 hours and cooled, and the salts were filtered off. The filtrate was evaporated under reduced pressure to remove the solvent, and the residue was dissolved in dichloromethane. The solution was dried (Na2SO4), filtered and evaporated. Distillation of the residue afforded n-butyl 2-bromoacrylate (196 g; 90%), b.p. 90°/15 mmHg. round bottom flask fitted with a thermometer, condenser, stirrer and inlet for nitrogen under reflux for 8 hours cooled the salts were filtered off The filtrate was evaporated under reduced pressure to remove the solvent the residue was dissolved in dichloromethane The solution was dried (Na2SO4) filtered evaporated Distillation of the residue

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: n-Butyl 2,3-dibromopropionate (144 g, 0.5 mole) containing p-methoxyphenol (0.5 g) was stirred vigorously under nitrogen and at room temperature, whilst 20% w/v aqueous caustic potash solution was slowly added. The course of the dehydrobromination was constantly monitored by gas-liquid chromatography. From time to time the reaction mixture was allowed to separate and the almost neutral aqueous phase discarded, in order to maintain that effective concentration of the added base. When more than 95% of the starting material had been consumed, the reaction was stopped and the lower organic layer run off and washed with water. After drying (Na2SO4), the crude product was distilled to give a main fraction which was n-butyl 2-bromoacrylate (yield 72%), bp 92°/17 mmHg. was slowly added to separate to maintain that effective concentration of the added base When more than 95% of the starting material had been consumed washed with water After drying (Na2SO4) the crude product was distilled to give a main fraction which