DFT study on the Stereoselectivity of Asymmetric Synthesis of C, N-Cyclic Azomethine Imines with Allyl Alkyl Ketones

Based on the density functional theory, the stereoselectivity of the asymmetric synthesis of tetrahydroisoquinolinopyrazole derivatives by the cycloaddition reaction of C, N-cyclic azomethine imines with allyl alkyl ketones which was catalyzed using a chiral primary amine is studied theoretically. The results demonstrate that the four chiral transition states (TS-1R2R, TS-1R2S, TS-1S2R and TS-1S2S) are formed by the reaction of dienamine intermediate with C, N-cyclic azomethine imine, and the reaction barrier of TS-1R2S is in the lowest level (Delta G=6.98 kcal/mol). The consequence reveal that the 1R2S configuration product is formed by TS-1R2S transition state. Non-covalent interaction and electron density topology analysis show that the stereoselectivity of the chiral product is determined through van der Waals forces and hydrogen bond interaction of the transition state molecules.