Density functional theory study for epimerization of 2-benzyl-2-ethoxycarbonyl-cyclopentanolate ion

DFT studies were carried out in order to investigate the epimerization of 2-benzyl-2-ethyoxyl-carbonyl-cyclopentanol in etherified reaction. Stationary structures and energy were obtained at the B3LYP/6-311 + G(d,p) level. The loop will open when 2-benzyl-2-ethoxycarbonyl-cyclopentanol lose a H+, the -C-O- group will turn into a aldehyde group, and the other carbon atom and the carbonyl composite a Conjugate negative center. The energy of the trans conformation of the anion is 7.57 kJ/mol lower than the cis conformation, and the energy barrier of the conformation invert is only 3.05 kJ/mol. It shows the conformation invert reaction is controlled by thermodynamics and will happen easily. The result can explain the epimerization of 2-benzyl-2-ethoxycarbonyl-cyclopentanol in Williamson ether synthesis