Application of 3543-74-6, These common heterocyclic compound, 3543-74-6, name is Ethyl 4-(5-(bis(2-hydroxyethyl)amino)-1-methyl-1H-benzo[d]imidazol-2-yl)butanoate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
Preparation of Bendamustine Hydrochloride (Crude) (0099) Step 1: 4-{5-[Bis-(2-hydroxy-ethyl)-amino]-1-methyl-1H-benzoimidazol-2-yl}-butyric acid ethyl ester (27.0 kg) was dissolved in 270 kg chloroform. After cooling to 0 to 5 C., 19.2 kg thionyl chloride was added over about 1 hour. The mixture was warmed to 25 C.±5 C. and stirred for 20 to 24 hours. 75.6 kg hydrochloric acid (32% aqueous solution) was then added. After phase separation, the organic (lower) phase was removed. The product remained in the aqueous phase. (0100) Step 2: A suspension of activated charcoal in hydrochloric acid was added to the aqueous phase obtained in step 1. The mixture was heated over 1 hour to 85 to 90 C. and stirred for 4 to 5 hours at reflux. The suspension was then filtered and rinsed with aqueous hydrochloric acid. The solvent was distilled off under reduced pressure at a temperature not exceeding 65 C. 108 kg to 324 kg (108 kg preferred) of warm (35 to 45 C.) deionized water was added to induce crystallization. (0101) After crystallization, the mixture was cooled to 20 C±5 C. and stirred for an additional 1 to 2 hours or overnight. The product was collected by filtration on a filter dryer, washed with three portions each of 108 to 324 kg (108 kg preferred) deionized water and 108 to 216 kg (108 kg preferred) of cold acetone. The crude product was treated four times each with 54 to 108 kg (54 kg preferred) acetone at reflux for at least 1 hour, in the filter dryer. The suspension was filtered and the product dried at a temperature not higher than 40 C. under reduced pressure, to give 21.4 kg±2.1 kg bendamustine hydrochloride crude (70%±10%, calculated as dried substance). (0102) Step 3 (optional): The product obtained from step 2 was dissolved in hydrochloric acid (32% aqueous solution) and heated to reflux (85 to 90 C.) for at least 4 hours. To improve color, activated charcoal can be added to the hydrochloric acid and the mixture heated to reflux (85 to 90 C.) for at least 4 hours. With activated charcoal, the suspension was filtered and rinsed with aqueous hydrochloric acid. Solvent was distilled off under reduced pressure at a temperature not exceeding 65 C. The mixture was then diluted with deionized water. If no crystallization occurred within 15 min, the mixture was seeded. After crystallization, the suspension was stirred at 40 C.±5 C. for one hour, then cooled to 20 C.±5 C. After stirring an additional 1 to 2 hours at 20 C.±5 C., the product was collected by filtration, washed three times with cold deionized water, and at least three times with cold acetone. The crude product was treated four times with acetone at reflux for at least 1 hour. The suspension was filtered and the product dried at a temperature not higher than 40 C., under reduced pressure. Yield was of crude bendamustine hydrochloride was 80%±10%. Preparation of Purified Bendamustine Hydrochloride (0103) Bendamustine HCl crude (15.0 kg) was suspended with 0.45 kg activated charcoal in ethanol/water (vol/vol=97/3) at room temperature. The mixture was quickly warmed to 75 to 80 C. and stirred for not more than 10 min under reflux conditions. The mixture was filtered to remove the activated charcoal. After filtration, 33.0 kg of filtered acetone was added quickly at 40-50 C. to induce crystallization. (0104) After crystallization, the mixture was stirred for 30 to 60 min at 40-50 C., then cooled to 0 to 5 C., and stirred for at least an additional 30 min or overnight. The product was collected by filtration and washed with three 45 kg of cold acetone. After that, the crude product was treated 4 times each with 30 kg acetone at reflux for at least 1 hour. The suspension was filtered and the product dried at a temperature not higher than 40 C. under reduced pressure providing 11.3±1.5 kg bendamustine hydrochloride (75%±10%).
The synthetic route of 3543-74-6 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Cephalon, Inc.; Cooper, Martin Ian; Courvoisier, Laurent D.; Eddleston, Mark; McKean, Robert E.; (31 pag.)US2016/159748; (2016); A1;,
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