Fig. 7: Mechanistic investigations.

a Control experiment. b Envisioned catalytic cycle with the promoter system: [Ca], HFIP. c Acidity studies using Child’s method. Conditions: mixture of 2-cyclohexen-1-one (1 equiv), Ca(NTf2)2 (0 or 1 equiv) and HFlP (0 or 2 equiv) stirred at r.t. for 1 hour. d DFT computations. Computed free energy of the calcium-mediated reduction of methyl (E)−2-(phenylimine)acetate (ΔG298, kcal/mol; selected distances in Å; some hydrogen atoms have been omitted for clarity).