Silica-Supported Triptycene-Type Phosphine. Synthesis, Characterization, and Application to Pd-Catalyzed Suzuki–Miyaura Cross-Coupling of Chloroarenes

A silica-supported triptycene-type phosphine, Silica-TRIP, comprising a 9-phospha-10-silatriptycene (TRIP) and silica gel as a P-coordination center and a solid support, respectively, was synthesized and structurally characterized by nitrogen absorption measurements and solid-state CP/MAS NMR spectroscopy. Silica-TRIP exhibited a mono-P-ligating feature toward a Pd(II) complex, resulting in selective formation of a 1/1 Pd–P species even with an excess amount of the ligand. As a result, Silica-TRIP enabled Pd-catalyzed Suzuki–Miyaura cross-coupling reactions of chloroarenes under mild conditions, regardless of the moderate electron-donating nature of the triarylphosphine-based ligand.