The Sonogashira reaction (SNR) is undeniably the most applicable and efficient scheme in chemical synthesis, which involves the formation of C-C bonds by cross-coupling reaction (CCR) with terminal alkyne and halides of aryl or vinyl system. Typically, Pd serves as a catalyst for this reaction, with Cu serving as a co-catalysts and bases can be phosphine or amine. The applicability of such reactions lies in synthesizing medicines, heterocycles, and imitators in products of nature, biologically active complex compounds, nanomaterials, and other organic compounds. In this research, we could implement the SNR effectively without the need for the chemicals mentioned above reagents by using sodium aluminate (NaAlO2) as a base and catalyst as zinc under microwave irradiation (MWR) in water. The approach bears the potential to be in coherence with the principles of green chemistry and make reactions more atom-friendly. In order to achieve inexpensive and eco-friendly energy conditions, we developed one of the straightforward, concise, convergent protocols for sequential coupling and cyclization from Acetylenic species of quinoline-8-ol synthesized in situ by the CCR under MWR. Furthermore, the reaction used zinc as a catalyst and NaAlO2 as a base in the aqueous phase.

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The Sonogashira reaction (SR) which forms a C–C bond by cross-coupling a vinyl/aryl halide with a terminal alkyne, uses a palladium species as a catalyst, with a copper species as co-catalysts and a phosphine/amine as ligand/base in its actual form. This efficient reaction is beneficial in synthesizing heterocycles, nanomaterials, medicines and other complex molecules with biological functions. However, in this study, we were able to successfully execute the SR under microwave irradiation, using zinc aluminate (ZnAl2O4) as the catalyst, without using palladium, phosphines/amine as a ligand/base. This method, therefore, particularly useful for adhering to green chemistry principles and achieving atom-friendly reaction. In order to do this, we adopted a straightforward and concise method involving the development of a convergent protocol for sequential coupling and cyclization from Acetylenic 8-quinolinols generated in situ by the microwave-assistance SR to synthesize furo[3,2-h]quinolines, using ZnAl2O4 as a catalyst.