Green approach to Ullmann and Sonogashira cross-coupling reactions in water: Co-MOF as a robust and recyclable nanostructure

Abstract

This work focuses on developing a novel metal-organic framework (MOF) and its application as a catalyst for carbon-oxygen and carbon-carbon bond formation. The catalytic transformation of aromatic halides is particularly challenging and holds significant importance in modern organic synthesis. Cross-coupling reactions that create carbon-heteroatom linkages are highly valued due to their widespread use in synthesizing of bioactive compounds and natural products. Consequently, the search for improved heterogeneous catalytic systems remains a key research priority. In this study, a cobalt-based MOF was synthesized using 4-amino-3-hydroxybenzoic acid, terephthalaldehyde, and cobalt acetate. This stable, efficient metal organic framework was characterized via FT-IR, TGA, CHNO, TEM, ICP, FE-SEM and BET techniques. Comprehensive characterization confirmed its structure and catalytic potential for cross-coupling reactions. The developed protocol offers an efficient and straightforward approach for C–O and CC bond formation, delivering excellent product yields. This method was specifically applied to Ullmann and Sonogashira reactions, marking the first reported use of Co-MOF as nanostructure in such applications. The use of cobalt as a replacement for expensive palladium not only reduces costs but also significantly enhances the sustainability and accessibility of this process. Compared to existing methods, this strategy offers several advantages, including high efficiency, short reactions, catalyst stability, and minimal environmental impact. Additionally, the cobalt-MOF catalyst is easily recovered from reaction mixtures and retains its activity over multiple cycles, making it economical and environmentally friendly.