Salen-Pd(II)-Modified Stereoregular Polyisocyanides for Efficient Cooperative Catalysis of Suzuki Coupling Reaction.

Abstract

The development of high activity catalysts is crucial for improving industrial efficiency and mitigating environmental pollution. Polyisocyanides, with their pendant groups capable of forming ordered adjacent structures, offer a promising framework for designing cooperative catalysts that mimic the functionality of bimetallic centers. This unique structural arrangement is anticipated to significantly enhance catalytic activity in cooperative reactions. A novel approach to enhance the Suzuki coupling reaction using polymer-supported catalysts is presented. In this study, stereoregular polyisocyanides with Salen-Pd are functionalized to produce the Pd(II) metalized polyisocyanide (P1-Pd). The rigid backbone of the polymer facilitates the parallel alignment of Salen-Pd pendants, enabling double activation of the two substrates at an average distance of ≈1.2 nm. Catalytic efficiency is evaluated through Suzuki coupling reactions using various aryl halides. P1-Pd demonstrates high activity, yielding the desired products with excellent conversion rates. Conversely, the irregular polymer counterpart P2-Pd. P3-Pd and the small molecule control C1-Pd exhibit lower performance due to the absence of cooperative catalysis. To showcase the applicability of this strategy, Suzuki coupling is successfully conducted with outstanding yields for key drug intermediates, while also offering innovative insights for conjugated polymer synthesis.