Exploring green catalysis with Zn(II)-chitosan-alginate beads for pyran and pyranopyrazole synthesis

Biopolymers are natural and sustainable materials, offering numerous advantages in terms of environmental impact and abundant availability, including reduced dependency on non-renewable materials and minimized pollution associated with synthetic resources. These polymers exhibit high metal ion sorption capabilities and can be shaped into various forms. For these reasons, biopolymers like chitosan and alginate are currently under extensive study in heterogeneous catalysis. In this work, we prepared hybrid beads using a combination of chitosan microspheres, sodium alginate, and zinc ions (Zn-MCS-SA). The prepared beads were fully characterized and have demonstrated that can be used as a catalyst for the synthesis of derivatives of 4H-pyran and pyrano[2,3-c]pyrazole under greener reaction conditions. Moreover, the heterogeneous nature of the catalyst beads was proven, and good recyclability was demonstrated.