Diastereo- and Enantioselective Synthesis of Highly Functionalized Tetrahydropyridines by Recyclable Novel Bifunctional <i>C</i>₂-Symmetric Ionic Liquid–Supported (<i>S</i>)-Proline Organocatalyst

Abstract

An efficient, novel bifunctional C2-symmetric ionic liquid–supported (S)-proline organocatalyst 7 was developed for a one-pot, five-component reaction involving β-keto esters 8, aryl aldehydes 9, and aryl amines 10, affording highly functionalized tetrahydropyridines 11a–o by simultaneous generation of fives bonds and two stereogenic centers with extraordinary diastereo- and enantioselectivities (up to >99:1 dr, 95:5 er) in isopropanol with high yields (up to 92%). This protocol provides quick access to diverse enantio-enriched, highly functionalized diastereo- and enantioselective tetrahydropyridines in a green medium without any column chromatographic purification. The catalyst was recycled five times without significant loss of its catalytic activity