Diastereo- and Enantioselective Synthesis of Highly Functionalized Tetrahydropyridines by Recyclable Novel Bifunctional C2-Symmetric Ionic Liquid–Supported (S)-Proline Organocatalyst

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