With the rapid development and complex challenges of chemical substances, new drug synthesis pathways are usually the most effective.109-07-9,2-Methylpiperazine,as a common compound, the synthetic route is as follows.
Example 2 A reaction was performed as described for Example 1, except that the amount of benzyl chlorocarbonate used was changed from 8.45 g to 9.25 g (= 0.0533 mole, 1.07 molar times). As a result, the reaction yield of 1-benzyloxycarbonyl-3-methylpiperazine was 91.7% (based on the amount of 2-methylpiperazine) after lapse of 2 hours at 0 to 5C. Furthermore, the reaction solution was stirred at room temperature for further 12 hours and analyzed. As a result, the reaction yield was 94.5%. From the obtained reaction solution, 1-butanol was distilled away, and 30 g of water was added to the concentrate. The pH was adjusted to 11.2 using 48% sodium hydroxide. To the solution, 40 g of toluene was added, and the lower layer was removed. Subsequently, the upper layer was concentrated under reduced pressure to distill away toluene, for obtaining 11.1 g of a recovered solution. The obtained recovered solution was analyzed, and as a result, the intended 1-bunzyloxycarbonyl-3-methylpiperazine occupied 87.2 area %, and as for impurities, benzyl alcohol occupied 0.52 area %, 1-benzyl-4-benzyloxycarbonyl-2-methylpiperazine, 0.01 area %, 1-benzyl-2-methylpiperazine, 0.10 area %, and 1,4-dibenzyloxycarbonyl-2-methylpiperazine, 11.9 area % (solvent toluene, 1.9 area %). Therefore, the total of impurities was 6 liquid chromatography area %. Example 12 The reaction solution obtained by the same operation as in Example 2 was concentrated and 31 g of 1-butanol was distilled away under reduced pressure, being followed by addition of 30 g of water. Subsequently 35% hydrochloric acid water was used for adjusting the pH to 0.8. Then, 22 g of toluene was added, and stirring was carried out for 30 minutes. The upper layer was then removed, and the same amount of toluene was added again. The same operation was repeated for carrying out washing operation. Subsequently 48% sodium hydroxide aqueous solution was used to keep the pH of the reaction solution at 11.5. In this case, white turbidity occurred due to liberated 1-benzyloxycarbonyl-3-methylpiperazine. To the white turbid solution, 40 g of toluene was added, and stirring was carried out for 30 minutes. The lower layer was then removed, and the upper layer was concentrated under reduced pressure at 60 to 70C in temperature. Then, toluene was distilled away to obtain 10.13 g of 1-benzyloxycarbonyl-3-methylpiperazine. The obtained compound was analyzed. As a result, the intended 1-benzyloxycarbonyl-3-methylpiperazine accounted for 98.0 liquid chromatography area %. The impurities showed 0.40 liquid chromatography area % for benzyl alcohol, 0.04 liquid chromatography area % for 1-benzyl-4-benzyloxycarbonyl-2-methylpiperazine, 0.10 liquid chromatography area % for 1-benzyl-2-methylpiperazine and no detection for 1,4-dibenzyloxycarbonyl-2-methylpiperazine (1.46 liquid chromatography area % for solvent toluene). Therefore, the total of impurities was 0.55 liquid chromatography area %.Example 13 The reaction solution obtained by the same operation as in Example 2 was concentrated and 28 g of 1-butanol was distilled away under reduced pressure, being followed by addition of 30 g of water. Subsequently 35% hydrochloric acid water was used for adjusting the pH to 0.7. Then, 22 g of toluene was added, and stirring was carried out for 30 minutes. The upper layer was then removed, and the same amount of toluene was added again. The same operation was repeated for carrying out washing operation. Subsequently 48% sodium hydroxide aqueous solution was used to keep the pH of the reaction solution at 11.8. In this case, white turbidity occurred due to liberated 1-benzyloxycarbonyl-3-methylpiperazine. To the white turbid solution, 40 g of toluene was added, and stirring was carried out for 30 minutes. The lower layer was then removed, and the upper layer was concentrated under reduced pressure at 60 to 70C in temperature. Then, toluene was distilled away. Ten point three two grams of the obtained 1-benzyloxycarbonyl-3-methylpiperazine was placed in a 10 ml heart flask and distilled in vacuum. When the oil bath reached 145C, the removal by distillation started, and the temperature was raised finally up to 170C. The internal pressure ranged from 40 to 53 Pa, and the temperature at the column top ranged from 131 to 140C. The obtained compound was analyzed. As a result, the intended 1-benzyloxycarbonyl-3-methylpiperazine accounted for 99.7 liquid chromatography area %. The impurities showed 0.03 liquid chromatography area % for benzyl alcohol, 0.18 liquid chromatography area % for 1-benzyl-4-benzyloxycarbonyl-2-methylpiperazine, 0.04 liquid chromatography area % for 1-benzyl-2-methylpiperazine and no detection for 1,4-dibenzyloxycarbonyl-2-methylpiperazine (for solvent toluene either). Therefore, the total of impurities was 0.25 liquid chromatography area %.
109-07-9, 109-07-9 2-Methylpiperazine 66057, apiperazines compound, is more and more widely used in various fields.
Reference：
Patent; Toray Fine Chemicals Co., Ltd.; EP1548010; (2005); A1;,
Piperazine – Wikipedia
Piperazines – an overview | ScienceDirect Topics