Destabilizing Predictive Copper‐Catalyzed Click Reactions by Remote Interactions with a Zinc‐Porphyrin Backbone

Abstract

In order to obtain new supramolecular ligands that build up around a zinc‐porphyrin scaffold, we envisioned to access sulfonyl triazole intermediates by well‐known copper‐catalyzed click reactions. Unexpectedly, these triazole intermediates do not form due to the presence of the zinc‐porphyrin moiety at close proximity of the active copper species. Indeed, the copper catalyst undergoes a different chemo‐selective reaction pathway reacting with traces of alcohols or water from the media that behave as effective nucleophiles leading to sulfonyl imidates or sulfonyl amides covalently connected to the zinc‐porphyrin. We show that copper‐catalyzed click reactions can follow different reaction mechanisms when the catalytic events occur at close proximity of a zinc‐porphyrin unit which likely acts as a Lewis acid to stabilize otherwise inaccessible reaction intermediates.