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

An efficient, novel bifunctional C-2-symmetric ionic liquid-supported (S)-proline organocatalyst 7 was developed for a one-pot, five-component reaction involving beta-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.

Automated summary

An efficient and novel bifunctional ionic liquid-supported (S)-proline organocatalyst was developed for the synthesis of highly functionalized tetrahydropyridines. The reaction involved five components and allowed for the simultaneous generation of five bonds and two stereogenic centers with excellent diastereo- and enantioselectivities. The catalyst could be recycled five times without significant loss of activity.