Novel dabigatran etexilate intermediate as well as preparation method and application thereof
A technology of dabigatran etexilate and reaction is applied in the new intermediate of dabigatran etexilate and its preparation, and prepares the field of dabigatran etexilate, which can solve the problems such as complex operation and environmental pollution, and achieve simple purification method, The effect of high yield and mild reaction conditions
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Embodiment 1
[0069] Example 1: Preparation of 3-(2-chloroacetamido)-4-(methylamino)-benzoic acid
[0070]
[0071]6 g of 3-amino-4-methylaminobenzoic acid and 6.3 g of chloroacetic anhydride were added to 30 ml of tetrahydrofuran solution, and the reaction was stirred at room temperature for 3 hours. After filtration, the filtrate was concentrated under reduced pressure. To the concentrated solution, 15 ml of tetrahydrofuran was added, and the mixture was stirred for 30 minutes and filtered. The two batches of filter cakes were combined and dried to obtain 6 g of 3-(2-chloroacetamido)-4-(methylamino)-benzoic acid with a yield of 69%.
[0072] 1 H NMR (400MHz, DMSO-d 6 , ppm) δ12.20 (br s, 1H), 9.42 (s, 1H), 7.69 (dd, 1H, J=8.4Hz and J'=1.6Hz), 7.63 (d, J=1.6Hz, 1H), 6.61 ( d, J=8.4Hz, 1H), 4.28 (s, 2H), 5.94 (br s, 1H), 2.27 (d, J=8.8Hz, 3H).
Embodiment 2
[0073] Example 2: Preparation of 2-(chloromethyl)-1-methyl-1H-benzo[d]imidazole-5-carboxylic acid
[0074]
[0075] 6 g of 3-(2-chloroacetamido)-4-(methylamino)-benzoic acid was put into the reaction flask, 60 ml of methanol was added, 2 drops of concentrated hydrochloric acid were added dropwise, and the reaction was refluxed at 70° C. for 3 hours. After the reaction was completed, the reaction solution was cooled to 0° C. and filtered to obtain 4 g of 2-(chloromethyl)-1-methyl-1H-benzo[d]imidazole-5-carboxylic acid with a yield of 72.7%.
Embodiment 3
[0076] Example 3: Preparation of 2-(chloromethyl)-1-methyl-1H-benzo[d]imidazole-5-carboxylic acid
[0077]
[0078] Put 6 g of 3-amino-4-methylaminobenzoic acid and 6.3 g of chloroacetic anhydride into the reaction flask, and add 60 ml of ethyl acetate. Two drops of concentrated hydrochloric acid were added dropwise, and the mixture was refluxed at 80°C for 2 hours. After the reaction was completed, the reaction solution was cooled to 0°C and filtered. 5.1 g of 2-(chloromethyl)-1-methyl-1H-benzo[d]imidazole-5-carboxylic acid were obtained in a yield of 62.9%.
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