Continuous Flow Chiral Amine Racemization Applied to Continuously Recirculating Dynamic Diastereomeric Crystallizations
作者:Maria H. T. Kwan、Jessica Breen、Martin Bowden、Louis Conway、Ben Crossley、Martin F. Jones、Rachel Munday、Nisha P. B. Pokar、Thomas Screen、A. John Blacker
DOI:10.1021/acs.joc.0c02617
日期:2021.2.5
crystal growth, and dissolution. A variety of cyclic and acyclic amine salts were resolved using mandelic acid (MA) and ditoluoyl tartaric acid (DTTA) with higher resolvability (S = yield × d.e.) than the simple diastereomeric crystallization alone. Comparing resolvabilities, resolutions were 1.6–44 times more effective with the R3 process than batch, though one case was worse. Further investigation of this
已经开发出一种新的动态非对映异构结晶方法,其中连续分离母液,在固定床催化剂上外消旋,然后通过拆分-消旋-再循环(R 3)过程再循环到结晶器中。将消旋化与结晶化分离克服了原位使用催化剂的问题,这些催化剂遭受一系列条件,抑制和分离的冲突。通过[IrCp * I 2 ] 2的共价连接实现了连续消旋SCRAM催化剂以王氏树脂为固体载体,得到固定床催化剂。一种高级和多种仲级光学富集的胺已高效消旋,其停留时间与结晶相适应(2.25–30分钟)。该催化剂显示出比均相类似物更低的周转率(TOF),但重复使用显示出长寿命(例如40次循环,190小时),给出了可接受的周转数(TON)(最高4907)。发现在N-甲胺外消旋过程中甲胺的缓慢释放使催化剂失活,可以使用氢碘酸将其部分活化。R 3中实现了动态结晶通过不断去除溶解度较高的非对映异构体并提供溶解度较低的非对映异构体来完成这一过程。确定了非对映异构体的溶解度