A method for synthesizing eszopiclone
A synthetic method, hemiacetal technology, applied in organic chemistry, etc., can solve the problems of expensive esterase, long reaction time, and lack of industrial application value, and achieve the effect of easy-to-obtain catalyst, low production cost, and cheap catalyst
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Embodiment 1
[0021]
[0022] Add racemic hemiacetal 5.24g (20mmol) in the reaction flask, (R)-6-tert-butyl-2,3,5,6-tetrahydroimidazol[2,1-and]thiazole 0.37g ( 2mmol), Et 3 N 2.7 mL and 100 mL dry CH 2 Cl 2 . A solution of 2.5 mL of phenyl chloroformate dissolved in 100 mL of dichloromethane was slowly added dropwise at room temperature. After the addition was complete for about 1 hour, the reaction was stirred overnight at room temperature. Add 10%Na 2 CO 3 The pH of the solution was adjusted to 8-9, the organic layer was separated, and the aqueous layer was extracted with dichloromethane (100 mL×2). The combined organic layers were dried over anhydrous sodium sulfate, the solvent was removed under reduced pressure, and the residue was purified by silica gel column chromatography [V (ethyl acetate): V (petroleum ether) = 2: 3] to obtain (S)-hemicondensate Aldehyde phenyl carbonate 3.2g, yield 41.8%, ee value measured by Daicel Chiralcel AS-H chiral chromatographic column is 85%. ...
Embodiment 2
[0024] Using the same procedure as in Example 1, replace (R)-6- tert-butyl-2,3,5,6-tetrahydroimidazo[2,1-]thiazole was used as a catalyst to obtain 3.1 g of (S)-hemiacetal phenyl carbonate with a yield of 40.0% and an ee value of 82% .
Embodiment 3
[0026] Using the same procedure as in Example 1, replace (R)-6- tert-butyl-2,3,5,6-tetrahydroimidazo[2,1-]thiazole was used as a catalyst to obtain 2.7 g of (S)-hemiacetal phenyl carbonate with a yield of 35.0% and an ee value of 90% .
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