diethyl 2,5-dibromohexanedioate

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

Procedure: To a stirred solution of diethyl 2,5-dibromoadipate (4.5 g) in dimethylformamide (15 ml), sodium sulfide enneahydrate (3.9 g) was added under nitrogen atmosphere and the mixture was stirred for 5 hours under ice-cooling. To the reaction mixture, diethyl ether and water were added. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated in vacuo. The oily residue was purified by a silica gel column chromatography to give 2.1 g (72%) of 2,5-diethoxycarbonyltetrahydrothiophene. cooling The organic layer was washed with saturated sodium chloride solution dried over anhydrous magnesium sulfate concentrated in vacuo The oily residue was purified by a silica gel column chromatography

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

Procedure: To a stirred solution of diethyl 2,5-dibromoadipate (4.5 g) in dimethylformamide (15 ml), sodium sulfide enneahydrate (3.9 g) was added under nitrogen atmosphere and the mixture was stirred for 5 hours under ice-cooling. To the reaction mixture, diethyl ether and water were added. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated in vacuo. The oily residue was purified by a silica gel column chromatography to give 2.1 g (72%) of 2,5-diethoxycarbonyltetrahydrothiophene. cooling The organic layer was washed with saturated sodium chloride solution dried over anhydrous magnesium sulfate concentrated in vacuo The oily residue was purified by a silica gel column chromatography

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

Procedure: A solution of Diethyl meso-2,5-dibromoadipate (50 g, 139 mmol) in benzene (150 mL) was heated to reflux. Then heating was discontinued and benzylamine (50 mL) was added under stirring in 1 h. At the end of the addition, the mixture was refluxed for 20 h. After cooling down, the hydrobromide salt was filtered off and washed with benzene, and the benzene solution was evaporated. The residue was distilled under reduced pressure (180-190° C./0.3 mmHg) to give a product (39.9 g, 94%) as a yellow oil. Then heating At the end of the addition the mixture was refluxed for 20 h After cooling down the hydrobromide salt was filtered off washed with benzene the benzene solution was evaporated The residue was distilled under reduced pressure (180-190° C./0.3 mmHg)

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

Procedure: To a stirred solution of diethyl 2,5-dibromoadipate (4.5 g) in dimethylformamide (15 ml), sodium sulfide enneahydrate (3.9 g) was added under nitrogen atmosphere and the mixture was stirred for 5 hours under ice-cooling. To the reaction mixture, diethyl ether and water were added. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated in vacuo. The oily residue was purified by a silica gel column chromatography to give 2.1 g (72%) of 2,5-diethoxycarbonyltetrahydrothiophene. cooling The organic layer was washed with saturated sodium chloride solution dried over anhydrous magnesium sulfate concentrated in vacuo The oily residue was purified by a silica gel column chromatography