A kind of new preparation method of carnosine
A new method and carnosine technology, applied in the field of preparation of dipeptides, can solve the problems of large-scale use and promotion of unfavorable products, expensive protective agents, low total yield, etc., and achieve sufficient supply, lower production costs, and reaction selectivity. Good results
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Embodiment 1
[0021] A. Preparation of 1,3-oxazinane-2,6-dione (Ⅱ)
[0022] Add β-alanine (89g, 1.0mol) and anhydrous tetrahydrofuran (890g) into the reactor, stir well and then dropwise add anhydrous tetrahydrofuran solution of solid phosgene at room temperature (from 121g solid phosgene and 890g Anhydrous tetrahydrofuran configuration), after the dropwise addition, continue to stir the reaction at room temperature for 12 hours, after the reaction, remove most of the solvent tetrahydrofuran under reduced pressure, the residue is dissolved in ethyl acetate (178g), and the ethyl acetate layer is passed through 5% sodium bicarbonate solution, washed with water, dried over anhydrous sodium sulfate, filtered to remove the desiccant, and the solvent ethyl acetate was removed by distillation to obtain a residue of 1,3-oxazinane-2,6-dione (II) The crude product is 108.4g, and the yield is about 94.2%. The crude product was directly used in the next reaction without further purification. The det...
Embodiment 2
[0028] Other steps are the same as in Example 1, except that the preparation method of 1,3-oxazinane-2,6-dione (II) in step A is as follows:
[0029] Add β-alanine (89g, 1.0mol) and anhydrous tetrahydrofuran (450g) into the reactor, stir well and then add dropwise anhydrous tetrahydrofuran solution of solid phosgene at room temperature (from 101g solid phosgene and 450g Anhydrous tetrahydrofuran configuration), after the dropwise addition, continue to stir the reaction at room temperature for 8 hours, after the reaction, remove most of the solvent tetrahydrofuran under reduced pressure, the residue is dissolved in ethyl acetate (178g), and the ethyl acetate layer is passed through 5% sodium bicarbonate solution, washed with water, dried over anhydrous sodium sulfate, filtered to remove the desiccant, and the solvent ethyl acetate was removed by distillation to obtain a residue of 1,3-oxazinane-2,6-dione (II) The crude product is 92.6g, and the yield is about 80.5%. The crude ...
Embodiment 3
[0031] Other steps are the same as in Example 1, except that the preparation method of 1,3-oxazinane-2,6-dione (II) in step A is as follows:
[0032] Add β-alanine (89g, 1.0mol) and anhydrous tetrahydrofuran (750g) into the reactor, stir well and then dropwise add anhydrous tetrahydrofuran solution of solid phosgene at room temperature (from 110g solid phosgene and 750g Anhydrous tetrahydrofuran configuration), after the dropwise addition, continue to stir the reaction at room temperature for 10 hours, after the reaction, remove most of the solvent tetrahydrofuran under reduced pressure, the residue is dissolved in ethyl acetate (178g), and the ethyl acetate layer is passed through 5% sodium bicarbonate solution, washed with water, dried over anhydrous sodium sulfate, filtered to remove the desiccant, and the solvent ethyl acetate was removed by distillation to obtain a residue of 1,3-oxazinane-2,6-dione (II) The crude product is 100.9g, and the yield is about 87.7%. The crud...
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