Synthesis method of pimobendan
A technology of pimobendan and synthetic method, which is applied in the field of pharmaceutical chemical industry, can solve problems such as difficulty in realizing industrialized production, harsh production conditions, and long synthetic route, and achieve the effects of rapid preparation, increased reaction yield, and reduced reaction steps
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Embodiment 1
[0050] Step (1): Dissolve acetanilide (0.37moL, 50g) in 250ml carbon disulfide and stir at room temperature to obtain a colorless transparent solution, add anhydrous aluminum trichloride (100g) to it, heat to reflux for 1h, cool to room temperature, add 2 -Chloropropionyl chloride (75g), reacted at 50°C for 8h, concentrated under reduced pressure to recover the solvent, poured the residue into 600mL ice water of 1M dilute hydrochloric acid, stirred at room temperature for 1h, left it for 2h, precipitated a light yellow precipitate, filtered, collected the precipitate to obtain 4- Crude (2-chloropropionyl)-acetanilide was recrystallized from 95% ethanol to obtain 73.1 g of compound I (4-(2-chloropropionyl)-acetanilide), with a purity of 98.8%, a yield of 88%, and a melting point of 118-121°C.
[0051] Step (2): Mix the above-prepared compound I (45g) with 200mL of acetic anhydride, add 35mL of nitric acid dropwise under ice-cooling, after the addition is complete, react at 25°C...
Embodiment 2
[0057] Step (1): Dissolve acetanilide (50g) in 200ml dichloromethane and stir at room temperature to obtain a colorless transparent solution, add anhydrous aluminum trichloride (50g) to it, heat to reflux for 1h, cool to room temperature, add 2- Chloropropionyl chloride (50g), reacted at 40°C for 6h, concentrated under reduced pressure to recover the solvent, poured the residue into 600ml of 1M dilute hydrochloric acid, stirred at room temperature for 1h, stood for 2h, precipitated a light yellow precipitate, filtered, collected the precipitate to obtain 4-(2 -Chloropropionyl)-acetanilide crude product, the crude product was recrystallized with 95% ethanol to obtain 68.2g of compound I (4-(2-chloropropionyl)-acetanilide), with a purity of 98.5%, a yield of 82.2%, and a melting point of 118- 121°C.
[0058] Step (2): Mix compound Ⅰ (45g) with 150mL acetic anhydride, add 22.5mL nitric acid dropwise under ice bath, after the addition is complete, react at 20°C for 3h, add the rea...
Embodiment 3
[0064] Step (1): Dissolve acetanilide (50g) in 300ml carbon disulfide and stir at room temperature to obtain a colorless transparent solution, add anhydrous aluminum trichloride (150g) to it, heat to reflux for 1 hour, cool to room temperature, add 2-chloropropane Acyl chloride (100g), reacted at 46°C for 7h, concentrated under reduced pressure to recover the solvent, poured the residue into 600mL of 1M dilute hydrochloric acid, stirred at room temperature for 1h, left it for 2h, a light yellow precipitate precipitated, filtered, collected the precipitate to obtain 4-(2-chloro The crude product of propionyl)-acetanilide was recrystallized with 95% ethanol to obtain 70.7 g of compound I (4-(2-chloropropionyl)-acetanilide), with a purity of 98.8%, a yield of 85.3%, and a melting point of 118-121°C .
[0065]Step (2): Mix the above-prepared compound I (45g) with 315mL of acetic anhydride, add 45mL of nitric acid dropwise under ice-cooling, after the addition is complete, react at...
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