Aerobic Cu and amine free Sonogashira and Stille couplings of aryl bromides/chlorides with a magnetically recoverable Fe3O4@SiO2 immobilized Pd(II)-thioether containing NHC

Two value added C-C cross coupling reactions; Sonogashira and Stille couplings were achieved at milder conditions in the catalytic presence of a magnetically recoverable heterogeneous catalyst Fe3O4@SiO2@NHC<^>SPh-Pd(II). The catalyst was earlier reported for Suzuki-Miyaura reaction, and as an extension of its catalytic efficiency, the Stille and Sonogashira cross coupling reactions under aerobic condition has been explored in present report. The Sonogashira coupling of aryl bromides and terminal alkynes produced an excellent yield (similar to 96% at 0.25 mol% Pd) of the desired coupling product under copper and amines free conditions. Moreover, an excellent Stille coupling of readily available and more latent aryl chlorides and trialkylstannane was obtained (yields up to 95% at 0.25 mol% Pd) in absence of toxic fluorides additives. The broad substrate scope of the catalyst for both the coupling reactions and the magnetically recoverable feature of catalyst make this reaction highly desirable for industrial applications of present heterogeneous catalysis. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Two value added C-C cross coupling reactions, Sonogashira and Stille couplings, were successfully achieved using a magnetically recoverable heterogeneous catalyst Fe3O4@SiO2@NHC<^>SPh-Pd(II), without the need for copper and amines, and with the elimination of toxic fluoride additives, resulting in excellent yields. The catalyst has a broad substrate scope for both coupling reactions and a magnetically recoverable feature, making it highly desirable for industrial applications in present heterogeneous catalysis.