Synthesis of Quinolines from 2-amino aryl ketones: Probing the Lewis Acid Sites of Metal-Organic Framework Catalyst

Recent research underscores the significance of metal-organic frameworks as catalysts, owing to their structural adaptability, substantial surface areas, adjustable pore dimensions, and customizable catalytic sites. Using Friedländer synthesis, we evaluated the catalytic potential of three synthesized metal-organic framework materials, MIL-53(Al), MIL-101(Cr), and MOF-5(Zn), in quinoline derivative synthesis. MIL-53(Al) outperformed MIL-101(Cr) and MOF-5(Zn), highlighting the vital role of Lewis acidic sites (Al³⁺) in quinoline production. Potentiometric titration analyses revealed MIL-53(Al)'s superior Lewis acid strength. Reaction optimization involved varying temperatures, catalyst loading, reaction duration, and solvents. MIL-53(Al) exhibited four-cycle recyclability. Mechanistic insights underscored Lewis acid strength and the significance of sites. The Al-based catalyst proficiently facilitated Friedlander synthesis, yielding enhanced conversion and considerable physiologically active quinoline yields. The findings offer insights into diverse catalytic strategies and demonstrate the adaptability of metal-organic framework materials in varied chemical reactions.

Graphical Abstract

The Al-based Lewis acid MOF catalyst MIL-53(Al) efficiently facilitated the Friedlander synthesis, resulting in improved conversion and significant yields of physiologically active quinolines. These findings provide insights into versatile catalytic strategies and showcase the adaptability of MOFs in diverse chemical reactions.