Enantioselective Amination of 4-Substituted Pyrazolones Catalyzed by Oxindole-Containing Thioureas and by a Recyclable Linear-Polymer-Supported Analogue in a Continuous Flow Process
作者:Rodrigo Sánchez-Molpeceres、Laura Martín、Noelia Esteban、Jesús A. Miguel、Alicia Maestro、José M. Andrés
DOI:10.1021/acs.joc.3c02069
日期:2024.1.5
azodicarboxylates mediated by a novel quinine-derived thiourea with a 3,3-diaryl-oxindole scaffold is reported. This synthetic method furnished 4-amino-5-pyrazolones in high yields and with excellent enantioselectivities (up to 97:3 er) at room temperature in short reaction times. Moreover, a linear-polymer-supported bifunctional thiourea, synthesized by reacting a bifunctional aromatic monomer (biphenyl)
报道了一种新型奎宁衍生硫脲与 3,3-二芳基-羟吲哚支架介导的 4-取代吡唑啉酮与偶氮二羧酸盐的高效有机催化胺化。该合成方法在室温下、反应时间短的情况下以高产率和优异的对映选择性(高达 97:3 er)提供了 4-氨基-5-吡唑啉酮。此外,通过双官能芳香族单体(联苯)与靛红在超酸性介质中反应并进一步衍生化合成线性聚合物负载的双官能硫脲,被证明也是该α-胺化反应的有效多相有机催化剂。该方法的实用价值通过在回收实验中使用固定化催化剂来证明,无需额外的再活化即可保持活性,并且在流动过程中,可以以高收率和对映选择性合成克级的4-氨基-吡唑啉酮衍生物。