Sulfonic Acid-Anchored Isocyanurate-Based Periodic Mesoporous Organosilica (PMO-SO3H): A Highly Efficient and Recoverable Nanoporous Catalyst in Biginelli reaction

Multi-component reactions have attracted much attention as new research field for the synthesis of diverse and complex molecules especially heterocyclic compoundsin pharmaceutical and organic chemistry [1]. Nitrogen containing heterocyclic compounds are one of the most important compounds in the pharmaceutical field and are used as agents for the synthesis of new drugs [2]. Biginelli reaction is one of the most important and effective methods for the production of 3,4-dihydropyridin- 2(1H)-ones (DHPMs). DHPMs and their derivatives have attracted a lot of attention because having many biological and medicinal properties such as antiviral, antihypertension, anti-tumor, antibacterial and as calcium channel modulators [3]. The use of heterogeneous catalysts has been developed in recent years because its desirable properties and incorporating many principles of green chemistry. Mesoporous organosilica hybrids (PMOs) are an interesting and efficient category of these catalysts which prepared from bridged organosilane precursors ((R′O)3Si-RSi( OR′)3; R: organic bridging group, R′: methyl or ethyl). PMOs have large and adjustable pores, well-defined pore morphology and high surface area, which these properties allow facile and rapid diffusion of reagents into channels and improves reaction speed [4]. In this context, the preparation and catalytic application of sulfonic acid-anchored periodic mesoporous organosilica (PMO-SO3H) as a novel and efficient heterogeneous catalyst is described. Furthermore, the catalyst was also recovered and reused. The catalytic application of the PMO-SO3H nanoporous catalyst was then investigated in the Biginelli condensation of various aldehydes with β-ketoester⁄dimedon and urea/thiourea under solvent free condition [5].