(509y) Enantioselective Diels-Alder Reactions of Cyclopentadiene with Chiral Acrylates in Confined Nanospaces of Al-Mcm-48

Due to the high degree of regio- and stereoselectivity, the Diels-Alder (DA) reaction is a very powerful orbital-controlled pericyclic reaction and is widely used in synthetic organic chemistry and in the chemical industry. In the present work, ordered mesoporous aluminisilcates, such as Al-MCM-41 and Al-MCM-48 have been synthesized, characterized and used as heterogeneous catalyst for enantioselective diels-alder reaction of cyclopentadiene with chiral acrylates. Interestingly, the confined nanospaces of Al-MCM-48 acts as more reactive and enantioinductive heterogeneous catalyst than Al-MCM-41 particularly at low temperature. The high accessibility of reactants to Lewis acid catalytic sites, adsorption, spatial confinement in the nanoscopic reactors, 3-D network structure and effective diffusion of reactants play a crucial role in the present study. In addition, specific 3-D connected topology of Al-MCM-48 reduces the energy of the LUMO and provides a better overlap between HOMO of cyclopentadiene and the LUMO of the chiral ethylacrylate, according to the frontier molecular orbital theory.