Global Discovery Chemistry, Novartis Pharma AG, Basel, Switzerland.
Chirality. 2022 May;34(5):711-731. doi: 10.1002/chir.23426. Epub 2022 Feb 16.
The immobilization of cellulose 3,5-dimethylphenyl carbamate and amylose 3,5-dimethylphenyl carbamate on silica gel carrier was achieved by using photochemical and thermal processes. Both approaches provide an easy access to materials which were applied as chiral stationary phases (CSPs) for the chromatographic resolution of racemic molecules. The influence of parameters such as irradiation time and solvent on immobilization effectiveness was investigated. For the thermal processes, azo-bis-isobutyrontrile and di-tert-butyl peroxide were evaluated as radical initiators. The influence of parameters such as amount of radical initiator, solvent, temperature, and further handling operations on the immobilization rate was examined. The chiral recognition ability and the overall performance of the prepared immobilized phases were evaluated by injection of a series of racemic compounds onto packed HPLC columns. As there is almost no limitation of organic solvent types that can be used as mobile phases with the immobilized CSPs, they can be applied under chromatographic conditions which are prohibited with the corresponding non-bonded CSPs. This extended applicability considerably broadens the options for improving enantioselectivity and resolving chiral compounds which are not or only poorly soluble in the conventional mobile phases.
通过光化学和热过程，将纤维素 3,5-二甲基苯基氨基甲酸酯和淀粉 3,5-二甲基苯基氨基甲酸酯固定在硅胶载体上。这两种方法都为手性固定相（CSP）的材料提供了简便的制备途径，可用于对映异构体分子的色谱拆分。考察了诸如照射时间和溶剂等参数对固定化效率的影响。对于热过程，评估了偶氮二异丁腈和过氧化二叔丁基作为自由基引发剂。考察了诸如自由基引发剂用量、溶剂、温度以及进一步操作等参数对固定化速率的影响。通过将一系列外消旋化合物注入填充 HPLC 柱，评估了制备的固定相的手性识别能力和整体性能。由于几乎没有有机溶剂类型的限制，可以将其用作固定化 CSP 的流动相，因此可以在传统流动相不允许的色谱条件下使用。这种扩展的适用性大大拓宽了改进对映选择性和拆分在常规流动相不溶或溶解度差的手性化合物的选择。
