Preparation method of cisapride key intermediate
An intermediate and key technology, applied in the field of medicinal chemistry, can solve the problems of long synthetic route, low yield, and expensive starting materials, and achieve the effect of low equipment requirements, low reaction temperature, and easy access
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Embodiment 1
[0027] Step 1, the preparation of 3-methoxypyridine: under ice-bath conditions, add 113g 3-chloropyridine to 200mLN,N-dimethylformamide (DMF) solvent, add 75g potassium methylate in batches and stir until Completely dissolved. After the addition, the temperature was slowly raised to room temperature, and then heated to 70° C. to continue the reaction for 8 hours. After the reaction was completed, the DMF solvent was recovered by conventional operation to obtain 99 g of a light yellow liquid.
[0028] Step 2, preparation of 4-nitro-3-methoxypyridine: under ice-bath conditions, dissolve 55g of 3-methoxypyridine in 150mL of glacial acetic acid, add 120g of concentrated nitric acid dropwise for nitration reaction, after the dropwise addition , the reaction system was warmed up to room temperature and reacted for 5 hours. After the reaction, the reaction system was slowly poured into ice water, and the glacial acetic acid was recovered by conventional operation, and dried to obtain ...
Embodiment 2
[0033] Step 1, preparation of 3-methoxypyridine: under ice-bath conditions, add 75g of 3-chloropyridine to 200mLN,N-dimethylformamide (DMF) solvent, add 75g of potassium methylate in batches and stir until Completely dissolved. After the addition, the temperature was slowly raised to room temperature, and then heated to 60° C. to continue the reaction for 9 hours. After the reaction was completed, the DMF solvent was recovered by conventional operation to obtain 40 g of a light yellow liquid.
[0034] Step 2, preparation of 4-nitro-3-methoxypyridine: under ice-bath conditions, dissolve 36g of 3-methoxypyridine in 150mL of glacial acetic acid, add 120g of concentrated nitric acid dropwise for nitration reaction, after the addition is complete , the reaction system was warmed up to room temperature and reacted for 4 hours. After the reaction, the reaction system was slowly poured into ice water, and the glacial acetic acid was recovered by conventional operation, and dried to obt...
Embodiment 3
[0039] Step 1, preparation of 3-methoxypyridine: under ice-bath conditions, add 150g 3-chloropyridine to 200mL N,N-dimethylformamide (DMF) solvent, add 75g potassium methylate in batches and stir until Completely dissolved. After the addition, slowly warm up to room temperature, and then heated to 80°C to continue the reaction for 7h. After the reaction, the DMF solvent was recovered by conventional operation to obtain 107g of light yellow liquid.
[0040]Step 2, the preparation of 4-nitro-3-methoxypyridine: under ice-bath conditions, dissolve 72g of 3-methoxypyridine in 150mL of glacial acetic acid, add 120g of concentrated nitric acid dropwise for nitration reaction, after the dropwise addition , the reaction system was warmed up to room temperature and reacted for 6 hours. After the reaction, the reaction system was slowly poured into ice water, and the glacial acetic acid was recovered by conventional operation, and dried to obtain 86 g of a yellow solid.
[0041] Step 3, ...
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