仲醇氧化:Oxone/cat.pre-IBS的工艺应用(120kg)

文摘   2024-12-13 07:03   天津  
案例介绍
  • 化合物19氧化制备化合物12
氧化剂的筛选
  • 不同氧化剂的筛选和高碘氧化试剂的认识
  • pre-IBX原位氧化制备IBX和pre-IBS原位氧化制备IBS

  • Swern氧化数据不错,工艺应用相对很差(entry 1)
  • DMP氧化数据还行,但是安全因素大(entry 2)
  • 两种高碘氧化试剂搭配Oxone数据不错,相比之下Oxone/cat.pre-IBS数据很好。

诱导期的研究
  • 氧化反应,最怕的就是诱导期
  • 本案例诱导期2-5小时,诱导期的不同主要源于Oxone的粒度分布,粒度越小,诱导期越短。
  •  尝试反应加水,缩短诱导期,设计思路是基于Oxone的溶解,实现了目的。
  • 尝试加硫酸钠和水,缩短诱导期,设计思路是基于硫酸钠会结合水,然后缓慢释放水。实现了目的,但是最后转后差一点。

改变底物后的研究结果
对应实验操作
A clean and dry reactor was charged with 22(144.0 kg, 68.1 wt %, 388 mol, 1.00 equiv), acetonitrile (813.0kg), water (7.2 kg), and 2-iodobenzenesulfonic acid (5.51 kg,20 mol, 0.05 equiv). The reactor was inerted with N2. The reaction temperature was raised to 60−65 °C with agitation.
Oxone (268.3 kg, 873 mol, 2.25 equiv) was charged in portions (10−15 kg each portion) while the internal temperature was controlled at <70 °C. Sample was taken to check the completion of reaction after agitation at 60−65 °C for 4−8 h. The temperature was adjusted to 20−30 °C. 
The reaction mixture was filtered, and the cake was transferred into another clean and dry reactor and agitated with n-heptane (514.5 kg) at 10−30 °C for 1−3 h. The mixture was filtered, and the cake was rinsed with n-heptane (154.3 kg). All the mother liquor and washes were combined and agitated for 0.5−1 h at 10−30 °C. The layers were separated. The lower layer was transferred into another clean and dry reactor and extracted with heptane (352.0 kg) twice. All organic phases were combined and washed with a Na2SO3 aqueous solution (30.0 kg of Na2SO3 dissolved in 175.0 kg of H2O). A sample was taken from the upper phase and checked with potassium iodide starch testing paper. The organic layer was further washed with water (205.8 kg). The organic phase was concentrated under vacuum at <40 °C to remove most of the solvent to give 25 as a yellow liquid (119.6 kg, 74.6 wt %, 89.9 A%, 92% yield). A pure sample of 25 was obtained by flash chromatography on SiO2 of the crude product.

参考文献
https://doi.org/10.1021/acs.oprd.3c00363

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