Efficient Ultrasound-Assisted Green Synthesis of beta-Enaminones Using Cost-Effective Coal Tar-Based POP: A Sustainable Approach with Molecular Docking Insights into Antibacterial Potential

Abstract

INTRODUCTION: A green, sustainable, and ultrasound-assisted method for the synthesis of beta-enaminone derivatives was developed. This study introduces a sulfur-enriched coal tar-based porous organic polymer (CTHP-SES) as a highly efficient, metal-free catalyst, providing an environmentally friendly alternative to conventional synthetic methods. METHODS: The synthesis employed CTHP-SES, a metal-free catalyst characterized by a microporous framework and thiol-functionalized acidic sites. Optimization studies were conducted to determine the optimal reaction conditions, including solvent selection and catalyst loading. Propylene carbonate was identified as the most suitable solvent, while 20 mg of catalyst afforded efficient conversion under mild, ultrasound-assisted conditions. RESULTS: The optimized protocol enabled the synthesis of beta-enaminones in yields of up to 93 within only 20 minutes. The CTHP-SES catalyst exhibited a broad substrate scope, efficiently converting a wide range of aromatic and aliphatic amines. Notably, it outperformed conventional catalysts such as ZnCl(2), AlCl(3).6H(2)O, FeCl(3), and p-TSA in terms of catalytic activity and recyclability, retaining more than 71 of its initial efficiency after seven reuse cycles. DISCUSSION: The excellent catalytic performance of CTHP-SES is attributed to its acidic framework, which facilitates ketone activation. Its superior activity and reusability highlight its potential as a sustainable green catalyst. Molecular docking studies against the CTX-M-64 enzyme revealed strong antibacterial potential for the synthesized beta-enaminones, with compound E-17 exhibiting the highest binding affinity (-8.22 kcal mol(-)(1)), suggesting promising therapeutic applications. CONCLUSION: This study successfully established a sustainable and efficient ultrasound-assisted protocol for the synthesis of beta-enaminones using the CTHP-SES catalyst. The synthesized beta- enaminones demonstrated significant antibacterial potential, highlighting the dual applicability of this work in both catalysis and medicinal chemistry.