Augmenting Basicity and Nucleophilicity by Smart Combination of Electronic Effects: Strong Metal-Free Bases and New Zwitterionic Organocatalysts.

摘要

In the course of our study towards rational design and synthesis of new highly base resistant organic cations, we identified aromaticiry as a key factor contributing to the stability of 2-aminoimidazolium moiety in strongly basic media at high temperature. Protonation of the compound I leads to 671-aromatic stabilization of the resulting 2-aminoimidazolium cation A. This would imply a significant contribution of the dipolar resonance to the ground state structure of the base I and hence to its enhanced thermodynamic basicity.