Asymmetric α-Amination of 4-Substituted Pyrazolones Catalyzed by a Chiral Gd(OTf)<sub>3</sub>/<i>N,N′</i>-Dioxide Complex: Highly Enantioselective Synthesis of 4-Amino-5-pyrazolone Derivatives
The asymmetric α-amination of 4-substituted pyrazolones with azodicarboxylates was investigated for the first time, employing an N,N′-dioxide gadolinium(III) complex as the catalyst. The novel transformations exhibited high yield, and 4-amino-5-pyrazolone derivatives bearing a chiral quaternary center were obtained in excellent yields (up to 99%) and enantioselectivities (90%−97% ee) for a broad scope
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 bifunctionalthiourea, synthesized by reacting a bifunctional aromatic monomer (biphenyl)