A kind of preparation method of dabigatran etexilate intermediate
A technology for dabigatran etexilate and intermediates, which is applied in the field of preparation of dabigatran etexilate intermediates, and can solve the problems of long reaction cycle, high corrosion of production equipment, and low purity of compound 1
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Embodiment 1
[0027] A kind of preparation method of dabigatran etexilate intermediate, comprises the steps:
[0028] (1) Dissolve 480g of compound 2 in 2500mL of tetrahydrofuran (stir at room temperature until completely dissolved), cool the reaction solution to -5°C, slowly add 1mol / L lithium hexamethyldisilazide tetrahydrofuran solution 1200mL dropwise, About 50 minutes to drip;
[0029] (2) After the dropwise addition, keep the temperature of the reaction solution at 15-20°C, detect by HPLC, if the remaining amount of compound 2 is below 1.0%, stop the reaction (timed reaction time is about 2 hours);
[0030] (3) Continue to cool down to below 5°C, add concentrated hydrochloric acid (density 1.179g / cm 3 ) until the pH of the reaction solution is between 2-3, add 1200mL water and 800mL methyl tert-butyl ether, stir and mix, separate the water phase (add concentrated hydrochloric acid: the basic impurities generated can be removed, compound 1 is dissolved in acidic conditions In water, ...
Embodiment 2
[0033] Replace the 1 mol / L tetrahydrofuran solution of lithium hexamethyldisilazide in step (1) with the tetrahydrofuran solution of 1 mol / L sodium hexamethyldisilazide, and refer to Embodiment 1 for others to obtain light yellow Oil 442g, yield 88.6%.
Embodiment 3
[0035] The tetrahydrofuran in step (1) was replaced with acetonitrile, and other references were made to Implementation 1 to obtain 376 g of light yellow oil, with a yield of 75.3%.
[0036] The compound 1 oil obtained in any of the above examples was dissolved in acetone, and an equimolar p-toluenesulfonic acid was added to obtain a white solid powder, which was the p-toluenesulfonate of compound 1. 1 HNMR (DMSO) see figure 1 , 1 HNMR(DMSO, 30℃400MHz)[ppm] δ1.12 (t, 3H), δ2.29(s, 3H) ,δ2.68(t,2H),δ3.76(s,3H),δ3.98 (t,2H),δ4.22(t,2H),δ4.65(d,2H),δ6.86(m,2H),δ6.90(m,1H),δ7.12(m,3H) ,δ7.16(m,1H),δ7.36(m,1H),δ7.40(m,1H),δ7.49(m,3H),δ7.55(m,1H),δ7.62( m, 2H), δ8.38 (m, 3H) δ8.80 (s, 2H).
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