Aerobic Cu/Amine Free Sonogashira and Stille Couplings with a Magnetically Recoverable Fe3O4@SiO2 Im

Tetrahedron Letters, 2021, In Press

Two value added C-C cross coupling reactions; Sonogashira and Stille couplings were achieved by use of a magnetically recoverable heterogeneous catalyst Fe3O4@SiO2@NHC^SPh-Pd(II) at mild and feasible condition. The Pd-catalyst was earlier reported for a terrific potential for catalysis in water mediated Suzuki-Miyaura reaction at ambient temperature. In present study, the catalyst has been explored for the Stille and Sonogashira cross coupling reactions under aerobic condition. The Sonogashira coupling of aryl bromides and terminal alkynes produced an excellent yield (~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, magnetically recoverable feature providing long life making it a highly desirable catalyst for industrial applications in heterogeneous catalysis, are some of the novel features of current catalyst.