Wednesday, November 7, 2007
509y

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

Santosh Singh Thakur1, Jeong Kuk Shon1, Sung Soo Kim1, Sang Soo Park1, Hyung Ik Lee1, Do Hyun Ryu1, and Ji Man Kim2. (1) Chemistry, Sungkyunkwan University, Suwon, South Korea, (2) Sungkyunkwan Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, South Korea

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.