Limiting the Loading of Reactant 1,3-Cyclohexanedione Enables the Use of Less Catalyst.

We demonstrated that the loading amounts and concentrations of reactant 1,3-cyclohexanedione affect reaction rates and outcomes. In certain cases, reactions with higher concentrations of 1,3-cyclohexanedione were slower than those with lower concentrations. By minimizing the use of the cyclic 1,3-dione derivatives and by tuning the reaction concentration, the acid catalyst was reduced to 0.1 mol % to afford the desired products in high yields, and the reaction scope was expanded.