Trace amount Pd(ppm)-catalyzed Sonogashira, Heck and Suzuki cross-coupling reactions based on synergistic interaction with an asymmetric conjugated pyridinespirofluorene

Abstract

A multilayer film of (Pd²⁺/1)₁₀ was simply fabricated by Pd(II) and 2-Br-2′,7,7′-tri(4-pyridyl)-9,9′-spirobifluorene (1, Br-tpsf) through a layer-by-layer self-assembly method. The film loaded on a quartz slide as a catalyst reservoir could gradually release high active catalytic species to promote Sonogashira, Heck and Suzuki cross-coupling reactions, with extremely low Pd-loading of 11.0 × 10⁻⁶ mol% and high catalytic efficiency in EtOH–H₂O system.