A kind of preparation method of cilnidipine
A technology of cilnidipine and concentrated hydrochloric acid, which is applied in the field of preparation of cilnidipine, can solve the problems of not very good purity of finished cilnidipine, high single and total impurities, and achieve less single and total impurities and short synthesis time , Reasonable effect of process design
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Embodiment 1
[0034] To prepare cilnidipine follow the steps below:
[0035] 1. In a 250ml bottle, put in material a: methoxyethyl 2-(3-nitrophenylidene)acetoacetate (54g, 0.184mol) and material b: cinnamyl 3-amino-2-butenoate (40g, 0.184mol) and absolute ethanol (80g), warming up to reflux for 1 hour;
[0036] 2. Add 3.68 ml of concentrated hydrochloric acid (>35%) to the reaction system in step 1, continue to reflux for 1 hour, then cool and crystallize, and filter to obtain the crude product of cilnidipine;
[0037] Crude yield: 80.7g
[0038] Yield 88.98%,
[0039] M.P.: 106.1~106.7℃
[0040] Maximum simple impurity: 0.2%
[0041] A total of 10 small impurity peaks
[0042] Content: 99.25%
[0043] 3. According to the weight ratio of ethanol:crude product=3:1, use absolute ethanol to recrystallize the crude product cilnidipine obtained in step 2 to obtain the finished product cilnidipine.
[0044] Yield 91.3%,
[0045] M.P.: 107.2~108.1℃
[0046] Maximum Simplex: 0.1380%
[00...
Embodiment 2
[0051] To prepare cilnidipine follow the steps below:
[0052] 1. In a 2500ml bottle, put in material a: 2-(3-nitrophenylidene) methoxyethyl acetoacetate (432g, 1.47mol) and material b: cinnamyl 3-amino-2-butenoate (400g, 1.84mol) and n-butanol (800g), warming up and refluxing for 0.5 hours;
[0053] 2. Add 46 ml of concentrated hydrochloric acid (>35%) to the reaction system in step 1, continue to reflux for 0.5 hours, then cool and crystallize, and filter to obtain the crude product of cilnidipine;
[0054] Crude product yield: 618g
[0055] Yield 85.19%,
[0056] M.P.: 107.2~107.9℃
[0057] Maximum Simplex: 0.28%
[0058] A total of 12 small impurity peaks
[0059] Content: 98.56%
[0060] 3. According to the weight ratio of ethanol:crude product=3:1, use absolute ethanol to recrystallize the crude product cilnidipine obtained in step 2 to obtain the finished product cilnidipine.
[0061] Yield 89.8%,
[0062] M.P.: 107.1~108.0℃
[0063] Maximum Simplex: 0.1380%
[...
Embodiment 3
[0068] To prepare cilnidipine follow the steps below:
[0069] 1. In a 500ml bottle, put in material a: methoxyethyl 2-(3-nitrophenylidene)acetoacetate (65g, 0.221mol) and material b: cinnamyl 3-amino-2-butenoate (40g, 0.184mol) and tetrahydrofuran (90g), heated and refluxed for 2 hours;
[0070] 2. Add 2.76 ml of concentrated hydrochloric acid (>35%) to the reaction system in step 1, continue to reflux for 3 hours, then cool and crystallize, and filter to obtain the crude product of cilnidipine;
[0071] Received product: 77.8g
[0072] Yield 85.78%,
[0073] M.P.: 106.0~106.8℃
[0074] Maximum Simplex: 0.27%
[0075] A total of 11 small impurity peaks
[0076] Content: 99.21%
[0077] 3. According to the weight ratio of ethanol:crude product=3:1, use absolute ethanol to recrystallize the crude product cilnidipine obtained in step 2 to obtain the finished product cilnidipine.
[0078] Yield 87.5%,
[0079] M.P.: 107.4~108.2℃
[0080] Maximum Simplex: 0.1460%
[0081...
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