Quantum Chemical Methods to Elucidate the Mechanism of a Diastereoselective Insertion-Addition Reaction of a Chiral Titanium (IV)-Schiff Base-Benzyl Complex with Hydroxyketones

B. Ramos, E.V. Castriciones
University of the Philippines,

Keywords: diastereoselective, Molecular Modelling


We present our results on the quantum chemical studies carried out to elucidate the diastereoselective insertion-addition reaction of a chiral Titanium (IV)-Schiff Base-Benzyl complex (I) with hydroxyketones (II) to form the diastereoselective insertion product (III) in Figure 1. Results indicate both steric and electronic effects in controlling the highly specific formation of the diastereoselective product. Input data included single-crystal data from both the complex (I) and the final product (III). Geometry optimisation was carried out using PM7 Hamiltonian. A single-point energy calculation was performed at the DFT level (B3LYP, single ΞΆ basis functions). Possible reactivity sites were examined by investigating the condensed Fukui function of the complex, and mapping the HOMO and LUMO potential surfaces for I and II. A possible reaction pathway based on single-energy point computation is shown (Figure 2.) and can serve as a guide in determining the transition states (and other potential intermediates).