Method of preparing eszopiclone intermediate 6-(5-chloro-2-pyridyl)-5,7-dioxy-6,7-dihydro-5H-pyrrolo[3,4-b] pyrazine
A technology for eszopiclone and intermediates, which is applied in the field of preparation of intermediates for the anti-insomnia drug eszopiclone, and can solve problems such as purchase and use restrictions
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Embodiment 1
[0016] Under the protection of dry nitrogen, chloroform (560mL), 3-(5-chloropyridine-2-amino)formylpyrazine-2-carboxylic acid (II, 55.7g, 0.2mol), diiso Propylamine (23.3g, 0.23mol), stirred to dissolve. The temperature was lowered to -20°C, methyl chloroformate (23.87 g, 0.22 mol) was added dropwise, samples were taken every half hour for HPLC monitoring, and the reaction was terminated until the raw material content was <1%.
[0017] The reaction solution was washed with hydrochloric acid (10% 150 mL×2), water (200 mL×3). The organic phase was separated, dried with anhydrous sodium sulfate (4g) for 4h, and activated carbon (5g) was decolorized at room temperature for 2h. Suction filtration, concentration under reduced pressure to remove all solvents, to obtain 50.5 g of off-white solid, yield 96.9%, HPLC content 98.5%. mp239~241℃. 1 H NMR (CDCl 3 , 300MHz), δ: 9.06(s, 2H, ArH), 8.67(d, 1H, PyH, J=2.58Hz), 7.93(dd, 1H, J=8.46Hz & 2.52Hz, PyH), 7.49(d, 1H, 8.52Hz, PyH). (...
Embodiment 2
[0019] Reaction solvent is benzene, and all the other are with embodiment 1.
[0020] Yield 95%, content 99%.
Embodiment 3
[0022] Reaction solvent is toluene, and carboxyl activator is ethyl chloroformate, and all the other are with embodiment 1.
[0023] Yield 93%, content 98%.
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