Enantiomerically enriched 1-phenylethylamines
An enantiomer enrichment technology, applied in the purification/separation of amino compounds, medical preparations containing active ingredients, organic racemization, etc.
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Embodiment 1
[0100] Preparation of 3-nitro-N-methoxyiminoacetophenone
[0101] 240.0 g (1.453 mol) of 3-nitroacetophenone were suspended in 1200 ml of ethanol at room temperature. A solution of 132.0 g of O-methane hydrochloride in 120 ml of water was added dropwise to the resulting suspension over 45 min. The resulting reaction mixture was heated to boiling and stirred at this temperature for 4 h. The resulting suspension was then filtered hot. The resulting filtrate was cooled to room temperature for 12h. The colorless solid which precipitated during this time was filtered off with suction using a frit and washed 3 times with 100 ml of ethanol each time. The resulting product was dried at 50° C. under a pressure of 100 mbar for 2 h. 235.3 g of a yellowish solid were obtained (83.2% of theory).
Embodiment 2
[0103] Preparation of 1-(3-nitrophenyl)ethylamine
[0104] a) Activation with acetic acid
[0105] First add 100 g of dry tetrahydrofuran under an argon atmosphere. To this solvent was added 3.78 g (0.10 mol) of sodium borohydride. The resulting suspension was stirred at room temperature for 15 min. Afterwards, 6.0 g (0.10 mol) of acetic acid were added dropwise at 20° C., during which time a vigorous formation of gas began. Then, a solution of 4.86 g (0.025 mol) 3-nitro-N-methoxyhydrogenideneacetophenone in 40 ml tetrahydrofuran was added over 20 min. The resulting reaction mixture was stirred at room temperature for 2 h, then heated to reflux for 2 h. Thereafter, the resulting mixture was cooled to 10°C, and 60 ml of water was added dropwise at this temperature while stirring. Solvent was removed on a rotary evaporator. The resulting residue was dissolved in 150 ml of water, and adjusted to pH 1 with 10 ml of concentrated hydrochloric acid. The resulting aqueous solut...
Embodiment 3
[0111] Preparation of (S)-1-(3-nitrophenyl)ethylamine
[0112] a) Crystallization with L-(+)-tartaric acid
[0113] 0.75 g (5.0 mmol) of L-(+)-tartaric acid was dissolved in 64 ml of methanol and the resulting solution was heated to reflux. A solution of 1.0 g (6.0 mmol) of 1-(3-nitrophenyl)ethanamine from Example 2 in 7.1 ml of methanol was metered in over 5 min, and the resulting mixture was then stirred at reflux for 15 min. The resulting solution was cooled to 50 °C for 40 min and then to 35 °C for 1.5 h. Then, the resulting solution was stored at 5°C for 4 days. The solid which precipitated during this time was filtered off. 0.5 g of an uncolored solid was obtained. It was suspended in 10 ml of water and adjusted to pH 10 with 0.9 ml of 10% sodium hydroxide solution. The resulting solution was extracted twice with 30 ml of dichloromethane. The solvents of the combined organic phases were removed with a rotary evaporator. This gave 0.3 g of (S)-1-(3-nitrophenyl)etha...
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Abstract
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