Rabeprazole synthesis
- Product Name:Rabeprazole
- CAS Number:117976-89-3
- Molecular formula:C18H21N3O3S
- Molecular Weight:359.44
![2-{[4-(3-Methoxypropoxy)-3-methylpyridine-2-yl]methylthio}-1H-benzimidazole](/CAS/GIF/117977-21-6.gif)
117977-21-6
117976-89-3
The general procedure for the synthesis of 2-(((4-(3-methoxypropoxy)-3-methylpyridin-2-yl)methyl)sulfinyl)-1H-benzo[d]imidazole from 2-(((4-(3-methoxypropoxy)-3-methylpyridin-2-yl)methyl)sulfinyl)-1H-benzo[d]imidazole was as follows: Example 6: 2.0 g of 2-[[[4-(3-methoxypropoxy)-3-methyl-2-pyridinyl]methyl]sulfinyl]-1H-benzo[d]imidazole was suspended in 36 mL of methanol at room temperature. Subsequently, 1.93 g of a 14 mL aqueous solution of 45% NaOH was added with stirring. 0.09 g of Na2WO4-2H2O oxidizing catalyst was dissolved in 0.66 g of 50% H2O2 aqueous solution and further diluted with 10 mL of water. The oxidizer/catalyst solution was slowly added dropwise to the reactant/base solution, and the dropwise process was completed in about 30 minutes while maintaining room temperature and continuous stirring. After the dropwise addition was completed, the reaction was continued with stirring for 10 minutes. Then, 10 mL of 10% Na2S2O3 aqueous solution was added and the reaction mixture was concentrated under reduced pressure to remove methanol. Finally, the pH was adjusted to about 8 by adding dilute aqueous acetic acid to form a precipitate. The precipitate was filtered, washed with water, and dried under vacuum to give rabeprazole in about 88% yield (LC purity >95%).
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Yield:117976-89-3 90%
Reaction Conditions:
Stage #1: 2,3-dimethyl-4-(3-methoxy-propoxy)pyridinewith n-butyllithium in tetrahydrofuran at -90 - -80;
Stage #2: (-)-menthyl 2-benzimidazolylsulphinate in tetrahydrofuran at -80 - -20;
Steps:
10
Example 10.- Preparation of rabeprazole, compound of general formula (11) wherein R2 is hydrogen, R4 is hydrogen, R5 is methyloxypropyloxy, and R6 is methyl; [Show Image] 4.26 g (21.8 mmol) of 2,3-dimethyl-4-(3-methoxy-propoxy)piridine were dissolved in 42 ml of anhydrous tetrahydrofuran at room temperature under inert atmosphere, and the solution was then cooled below - 90° C. 8.72 ml of a 2.5M solution of n-butyl lithium (21.8 mmol) were added dropwise and the temperature was maintained below -80° C. 2,3-dimethyl-4-(3-methoxy-propoxy)pyridine may be prepared in accordance with the process described in EP-A-0268956. After 30 minutes at this temperature, the mixture was slowly added to a solution of 2.0 g (6.24 mmol) of (-)-menthyl 2-benzimidazolylsulphinate, as obtained in Example 7, in 36 ml of tetrahydrofuran cooled below -80°C as well. Once the addition was completed, the resulting mixture was allowed to stand up to -20° C, then 100 ml of water were slowly added and it was allowed to reach room temperature. The reaction mixture was analyzed by HPLC, and conversion and yield were found to be 95% and 90% respectively.
References:
EP1992619,2008,A1 Location in patent:Page/Page column 16
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117976-89-3
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