Density functional studies on copper-catalysed asymmetric aziridination of diazoacetate with imines

Density functional theory has been used to study copper(I)-catalysed aziridination of diazoacetate with imines. All the intermediates and the transition states were optimised completely at B3LYP/6-31G(d) level. Calculation results confirm that copper(I)-catalysed aziridination of diazoacetate with imines is exothermic, and the total released Gibbs free energy is about ? 170 kJ/mol. Copper(I)-catalysed aziridination has two reaction modes: I and II, and thus the reaction mode I is dominant. The formation of the copper(I)–carbene–imine complex M3 (i.e. the attack of imines on copper–carbon(carbene) of copper–carbene intermediate M2) is the rate-determining step and the chirality-limiting step for copper-catalysed asymmetric aziridination. The reaction channel CA2 → M1a → TS1a → M2 → TS2a2 → M3a2 → TS3a2 → M4a2 → P1 is the most favourable one. The dominant products predicted theoretically are of (R)-chirality.