Green and sustainable synthesis of 3,4-Dihydropyrimidin-2(1H)-ones/thiones <i>via</i> the Biginelli reaction using L-arabinose as a renewable catalyst under solvent-free conditions

In the pursuit of sustainable methodologies in organic synthesis, the application of renewable and biodegradable catalysts has received significant attention. This work processes the synthesizing of 3,4-dihydropyrimidin-2(1H)-ones/thiones using L-arabinose, an environment-friendly catalyst <i>via</i> the Biginelli reaction in a solvent-free environment is reported herein. L-arabinose, a naturally occurring sugar, efficiently catalyzes the condensation reaction between β-ketoesters and aldehyde with urea or thiourea to form DHPMs with high yields and excellent atom economy. The reaction proceeds efficiently at mild temperatures, and the catalyst is easily regenerated, enabling multiple catalytic cycles. The use of L-arabinose avoids not only toxic solvents and metal catalysts but also processes green chemistry due to the exploitation of renewable resources. It is a significant step forward in the domain of sustainable catalysis and provides an environmentally benign and operationally simple procedure for the synthesis of DHPMs.