Synthesis of 8-Quinolinol Mannich Reaction Products
Objective: To synthesize biologically significant molecules applying Mannich reaction conditions.
Method: Equimolar quantities of corresponding aldehydes and amines were mixed with 8-quinolinol (8-HQ) in absolute ethanol at room temperature and pressure without using any catalyst. The reaction progress was monitored through TLC.
Results: The condensation of privileged 8-quinolinol (8-HQ, 1) with various substituted aldehydes and amines has resulted in the synthesis of ten products (2-11) under Mannich reaction conditions. These include four Mannich bases (2-5), three bis-products (6-8) and three imines (9-11). Nine of these derivatives are new and only one of them is known (11). The chemical characterizations of these molecules have been made through extensive study of 1H, 13C NMR and 2D NMR techniques. The long range interaction of H-4 and H-5 with C-10 in HMBC plot, revised the assignment of C-9 and C-10 in 8-quinolinol moiety of newly synthesized derivatives.
Conclusion: Several new derivatives of 8-quinolinol have been prepared under Mannich reaction condition without any catalyst. Exact characterization of these new molecules will serve as a reference spectral data for future study. As Mannich products generally possess significant biological properties, future pharmacological study may turn them as an important target for drug synthesis.
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