Bifunctional C2-symmetric ionic liquid-supported (S)-proline as a recyclable organocatalyst for Mannich reactions in neat condition

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 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.

[CMMIM][BF4 -] Ionic Liquid-Catalyzed Facile, One-Pot Synthesis of Chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-ones: Evaluation of Their Photophysical Properties and Theoretical Calculations

Herein, we have developed a novel synthetic route for the synthesis of chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-one derivatives 8a-q using an acid ionic liquid [CMMIM][BF₄ ^-] 4 via one-pot, three-component synthesis in aqueous ethanol at room temperature. A series of 17 derivatives have been successfully prepared with up to 93% yield. All the synthesized derivatives were well characterized using ¹H-NMR, ¹³C-NMR, and FT-IR spectral techniques. Additionally, the photophysical properties of 12 selected derivatives including molar extinction coefficient (ε), Stokes shift (Δυ̅), and quantum yield (Φ) varying from 0.52095 × 10⁴ to 0.93248 × 10⁴, 4216 to 4668 cm^-1, and 0.0088 to 0.0459, respectively, have been determined. Furthermore, the experimental data are supported by density functional theory (DFT) and time-dependent DFT calculations. Theoretical investigations showed a trend similar to experimental results.