Synthesis method for pramipexole impurity C
A synthesis method, the technology of pramipexole, applied in the field of synthesis of pramipexole impurity C, can solve problems such as harsh reaction environment, and achieve the effects of short preparation cycle, low cost and easy availability of raw materials
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Embodiment 1
[0047] Embodiment 1: A kind of synthetic method about pramipexole impurity C comprises the following steps:
[0048] ①Weigh 1.5g 2-methyl-3-oxopentanoic acid, 1.9g (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole and 2.3g triethylamine In a 100mL single-necked bottle, add 20mL DMF and stir evenly, then add 5.2g HBTU. The reaction system was stirred at room temperature for 3 h. After the reaction was completed, 50 mL of water was added for dilution, ethyl acetate was extracted three times, the organic phase was dried over anhydrous sodium sulfate, and the residue obtained after concentration was column chromatographed to obtain 2.4 g of a light yellow solid with a yield of 74.1%;
[0049] ②Weigh 1.2g of N-((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)-2-methyl-3-pentanamide in 50mL In the bottle, add 20 mL of tetrahydrofuran and stir to dissolve, then slowly add 5.3 mL of a tetrahydrofuran solution (2M) of borane dimethyl sulfide, and the above reaction mixture is refluxed...
Embodiment 2
[0055] Embodiment 2: A kind of synthetic method about pramipexole impurity C comprises the following steps:
[0056] ①Condensation of 2-methyl-3-oxopentanoic acid (Ⅲ) and (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (Ⅳ) to obtain N-((S) -2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)-2-methyl-3-pentanamide (Ⅴ), the required condensing agent is HBTU, the required base It is triethylamine, the solvent used is DMF, the reaction temperature is 30°C, the time is 3.5h, 2-methyl-3-oxopentanoic acid (Ⅲ): (S)-2,6-diamino -4,5,6,7-Tetrahydrobenzothiazole (Ⅳ)=1: 1.4;
[0057] ②N-((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)-2-methyl-3-pentanamide (Ⅴ) was reduced to obtain 1-( ((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)amino)-2-methyl-3-pentanol (VI), the reducing agent is boron Alkane dimethyl sulfide, the solvent used is tetrahydrofuran, the reaction temperature is 75°C, and the reaction time is 15h;
[0058] ③1-(((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-y...
Embodiment 3
[0060] Embodiment 3: A kind of synthetic method about pramipexole impurity C comprises the following steps:
[0061] ①Condensation of 2-methyl-3-oxopentanoic acid (Ⅲ) and (S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (Ⅳ) to obtain N-((S) -2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)-2-methyl-3-pentanamide (Ⅴ), the required condensing agent is DCC, the required base It is N,N-diisopropylethylamine, the solvent used is dimethyl sulfoxide, the reaction temperature is 50°C, the time is 1h, and 2-methyl-3-oxopentanoic acid (Ⅲ) is calculated in parts by weight: ( S)-2,6-diamino-4,5,6,7-tetrahydrobenzothiazole (IV)=1:1.6;
[0062] ②N-((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)-2-methyl-3-pentanamide (Ⅴ) was reduced to obtain 1-( ((S)-2-amino-4,5,6,7-tetrahydrobenzo[d]thiazol-6-yl)amino)-2-methyl-3-pentanol (VI), the reducing agent is selected from four Lithium aluminum hydride, the solvent used is ethylene glycol dimethyl ether, the reaction temperature is 100°C, and...
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