Preparation method of D-3-bromine-2-methyl propionyl-L-proline
A technology of methylpropionyl and D-3-, which is applied in the field of preparation of D-3-bromo-2-methylpropionyl-L-proline, can solve the problems of high production cost, long reaction steps, and yield. Low efficiency and other problems, to achieve the effect of shortening the production cycle, simplifying the production process, and reducing production costs
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[0028] Example 1 Preparation of D-3-bromo-2-methylpropionyl-L-proline (I)
[0029] Dissolve 57.5g (0.5mol) of L-proline in 200ml of water, cool to -5°C-0°C, add 20% NaOH solution dropwise under stirring conditions to adjust pH = 8.0-9.0, then add dropwise 3-bromo -2-Methylpropionyl chloride (IX) 92.7g (0.5mol), during the dropwise addition, continuously add NaOH solution to control the pH to remain at 8.0-9.0, after the dropwise addition, stir at this temperature for 0.5 hours, the reaction solution Wash 3 times with 200ml of ethyl acetate, remove the ethyl acetate layer, transfer the aqueous solution into a three-necked flask, acidify with concentrated hydrochloric acid to pH=2.0, react for 0.5 hours, let stand to separate layers, and separate to obtain the lower oil layer. Crystallize at 0°C to -5°C for 3-5 hours, then stand at -10°C for 10 hours, filter, wash the crystals with cold water, and dry at 55°C in a decompression oven to obtain D-3-bromo-2-methyl Propionyl-L-prol...
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