Synthetic method of pramipexole impurity B
A technology of pramipexole and synthesis method is applied in the field of preparation of pramipexole impurities to achieve the effects of simple process route and convenient operation.
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Embodiment 1
[0022] Step 1: Synthesis of (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropionamide
[0023]
[0024] At room temperature, (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (5.00g, 29.54mmol), triethylamine (8.97g, 88.63 mmol), propionic anhydride (9.61 g, 73.86 mmol) and DMAP (361 mg, 2.95 mmol). After the addition, the temperature of the system was raised to reflux for 2 hours. TLC detects that the reaction of raw materials is complete. Concentrate the reaction system to dryness, add 10 g of water and 40 g of ethyl acetate, stir vigorously for 3 hours, filter, and wash the filter cake with a little water and ethyl acetate. The obtained solid was transferred to an air blower at 60° C. and dried to constant weight to obtain 4.3 g with a yield of 51%.
[0025] Step 2: (S)-N 2 ,N 6 -Synthesis of dipropyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine
[0026]
[0027] Add (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropionamide (1.00g, 3.55mmol) to tetr...
Embodiment 2
[0029] Step 1: Synthesis of (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropionamide
[0030]
[0031] Add (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (5.00g, 29.54mmol), pyridine to 1,4-dioxane (50mL) at room temperature (11.53g, 88.63mmol), propionic anhydride (9.61g, 73.86mmol) and DMAP (361mg, 2.95mmol). After the addition, the temperature of the system was raised to reflux for 2 hours. TLC detects that the reaction of raw materials is complete. Concentrate the reaction system to dryness, add 10 g of water and 40 g of ethyl acetate, stir vigorously for 3 hours, filter, and wash the filter cake with a little water and ethyl acetate. The obtained solid was transferred to an air blower at 60° C. and dried to constant weight to obtain 3.8 g with a yield of 45.7%.
[0032] Step 2: (S)-N 2 ,N 6 -Synthesis of dipropyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine
[0033]
[0034] Add (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropane to 1,4-dioxa...
Embodiment 3
[0036] Step 1: Synthesis of (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropionamide
[0037]
[0038] At room temperature, (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (5.00g, 29.54mmol), N,N-diisopropyl Ethylamine (11.45 g, 88.63 mmol), propionic anhydride (9.61 g, 73.86 mmol) and DMAP (361 mg, 2.95 mmol). After the addition, the temperature of the system was raised to reflux for 2 hours. TLC detects that the reaction of raw materials is complete. Concentrate the reaction system to dryness, add 10 g of water and 35 g of ethyl acetate, stir vigorously for 3 hours, filter, and wash the filter cake with a little water and ethyl acetate. The obtained solid was transferred to an air blower at 60° C. and dried to constant weight to obtain 4.8 g with a yield of 57.7%.
[0039] Step 2: (S)-N 2 ,N 6 -Synthesis of dipropyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine
[0040]
[0041] Add (S)-N,N'-(4,5,6,7-tetrahydrobenzothiazole-2,6-diyl)dipropionamide (1.00g, ...
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