Zinc aluminate (ZnAl₂O₄) supported and catalyzed highly effective Suzuki–Miyaura cross-coupling reaction under microwave irradiation: Application to fused tricyclic oxa-aza-quinoline

This paper deals with the development of a concise, convergent protocol for obtaining diversely substituted Suzuki–Miyaura cross-coupling reaction of heteroaryl bromides and boronic acids under microwave irradiation using Zinc aluminate (ZnAl₂O₄) on fused tricyclic dihalo quinolones using as a solid support, base and as a catalyst in a solvent-free medium under microwave irradiation. The biological importance of biaryl quinolones are known to possess neuroprotective properties, coupled with the success in establishing a basic alumina-supported reaction for forming C–C bonds by Suzuki–Miyaura cross-coupling under microwave irradiation, prompted me to attempt use Zinc aluminate (ZnAl₂O₄) in lieu of traditional mineral bases efficiently promotes a solvent-free absence of any external catalyzed cross-coupling reaction under microwave irradiation. The operational simplicity, energy efficiency and general applicability of the procedure as well as the use of basicity of Zinc aluminate (ZnAl₂O₄) are expected to ensure future extension of this chemistry to the synthesis of other heterocyclic compounds of interest.