Critical Replacement of Super Critical Fluid HPLC for Chiral Separations

由于对映体具有相同的物理性质，所以定量手性的方法很复杂。在定量意义上使用旋光在小尺度上是不可靠的，并且对杂质高度敏感。手性移位试剂并不总是有效的，需要繁琐的滴定进入样品中，对于高度选择性的反应无济于事。手性固定相色谱是目前最好的选择，而超临界流体的使用对于提高分离速度和效率是必不可少的。根据我们的经验，使用SFC洗脱化合物的速度是传统高效液相色谱法的2-5倍。由于该仪器将在多个组之间共享，因此分析和开发反应条件的速度是至关重要的。 克鲁登实验室的主要部分研究对映体选择性和对映体特异性交叉偶联反应的发展。该项目以前依靠已有10年历史的SFC-HPLC在催化CC键连接后分离和鉴定对映体。经过9年的正常运行，这台仪器出现了一系列的故障，因COVID关闭而被送回母公司进行维修，归还给我们后仍然无法正常工作。目前，这使得我们无法测量样本中的手性，这威胁到了一名理学硕士学生、两名博士后和两名博士后研究员的工作。 如果没有所需的基础设施，另一个不可能实现的计划是在催化中使用手性纳米簇。在过去的6年里，Crudden一直在开发碳基NHC配体在材料科学中的用途，最终成功地合成了一系列纳米簇，最近描述了两个手性纳米簇。下一步是将这些应用于合成，如果没有所需的基础设施，这将是不可能的。斯塔姆科斯基小组在纳米团簇方面拥有丰富的经验，最近制备了一个手性Ag29团簇，但如果没有所需的基础设施，就不能将其用于任何事情。 皇后学院正在发展生物有机化学方面的实力，该计划的三个关键成员(泽切尔、豪和罗斯)的计划将受到严重影响，因为无法使用手性色谱。New Hire Howe正在研究酶的定向进化，包括制备设计酶以制备具有酶水平特异性的手性分子。Zechel正在研究用于立体特异性C-H激活的铁依赖加氧酶，Ross需要使用这台仪器来确定氨基酸的立体化学，这是她从细菌来源确定低丰度生物活性多肽结构的工作的一部分。如果没有所要求的基础设施，所有这些工作都不可能完成，基础设施也将成为五个小组中的HQP的极好的培训场地，并成为这些不同研究领域的HQP之间互动的接触点。

Methods to quantify chirality are complex since enantiomers have identical physical properties. The use of optical rotation in a quantitative sense is unreliable on small scales and highly sensitive to impurities. Chiral shift reagents are not always effective, require tedious titration into a sample and are not helpful for reactions that are highly selective. Chromatography with chiral stationary phases is by far the best alternative, and the use of super critical fluids is essential to increase the speed and efficiency of separation. In our experience, compounds elute 2-5 times faster using SFC compared to traditional HPLC. Since this instrument will be shared between multiple groups, speed of analysis and development of reaction conditions is essential. A major part of the Crudden lab studies the development of enantioselective and enantiospecific cross coupling reactions. This project previously relied upon a 10 year old SFC-HPLC to separate and identify enantiomers after catalytic CC bond connections. After functioning well for 9 years, this instrument suffered a series of breakdowns, was sent back to the parent company for repair over the COVID shutdown, and is still not functioning after being returned to us. For the time being, this leaves us unable to measure chirality in our samples, which is threatening the work of an MSc student, two PhD students, and two postdoctoral fellows. Another program that will be impossible without the requested infrastructure is the use of chiral nanoclusters in catalysis. Crudden has spent the last 6 years developing the use of carbon-based NHC ligands in materials science, culminating in the successful synthesis of a series of nanoclusters, most recently describing two chiral nanoclusters. The next step is the application of these in synthesis, which will not be possible without the requested infrastructure. The Stamplecoskie group has significant experience in nanoclusters and has recently prepared a chiral Ag29 cluster, but cannot use it for anything without the requested infrastructure. Queen's is developing a strength in bio-organic chemistry and the programs of three key members of this program (Zechel, Howe and Ross) will be severely impacted without access to chiral chromatography. New hire Howe is investigating directed evolution of enzymes, including the preparation of designer enzymes to prepare chiral molecules with enzyme-level specificity. Zechel is studying iron-dependent oxygenases for use in stereospecific C-H activation, and Ross needs access to this instrument to determine stereochemistry of amino acids as part of her work in structure determination of low abundance bioactive peptides from bacterial sources. None of this work will be possible without access to the requested infrastructure, which will also serve as an excellent training ground for HQP in the five groups, and a touchpoint for interactions between HQP from these different research areas.