Structure-nucleophilicity relationships for enamines.

摘要: The kinetics of the reactions benzhydryl cations with 22 enamines, three pyrroles, and indoles were investigated photometrically in dichloromethane. nucleophilicity parameters N slope s these electron-rich pi-systems derived from equation log k (20 degrees C)=s(E+N) compared nucleophilicities other (silyl enol ethers, silyl ketene acetals) carbanions. It is shown that nucleophilic reactivities enamines cover more than ten orders magnitude, comparable to ethers on low reactivity end carbanions high end. Since products N-attack are thermodynamically less stable reactants, observed rate constants refer formation carbon bond;carbon bonds. In some cases, equilibrium for iminium ions measured, which allow one determine intrinsic reactions.