Molecular recognition-based catalysis in nucleophilic aromatic substitution: a mechanistic study

Nucleophilic aromatic substitution for nitro-activated substrates in the presence of glymes and crown ethers is reported. The kinetic study reveals the many-sided nature of the polyether-catalyzed SNAr mechanism as well as the main features affecting the course of the reaction. Thus, the process can be efficiently controlled by the catalyst through a molecular-recognition process, being also strongly dependent on the electronic structure of the substrate and, therefore, giving rise to a versatile reaction system. The kinetic model proposed herein allows quantifying the fractions of reaction proceeding through the different routes. Information on the nature of the host-guest interaction between the catalyst and the substrate will also be extracted.