Pd on Metal Oxides and Activated Carbon for Suzuki-Miyaura Coupling

Significance

Supported palladium catalysts [Pd/C, Pd/Al₂O₃, Pd/TiO₂, Pd/CeO₂, Pd/zeolite (NaY)] led to high activity, short reaction times, and 100% selectivity in the Suzuki-Miyaura couplings. The Suzuki-Miyaura coupling of aryl bromides (R = CN, H, OH, OMe: 5 mmol) with phenylboronic acid (5.5 mmol) in the presence of commercially available 5% Pd/C (Evonik-Degussa AG: 0.005 mol%) and sodium carbonate (6 mmol) gave the corresponding coupling products in 100% GC yield (1.5-2 h, 120 ˚C). Palladium supported on Al₂O₃ and TiO₂ showed similar activity as Pd/C (2 h, Pd/Al₂O₃ = TON: 19200, selectivity: 100%; Pd/TiO₂ = TON: 19400, selectivity: 100%) in the Suzuki-Miyaura coupling of 4-bromoanisole with phenylboronic acid. Pd/CeO₂ and Pd/zeolite (NaY) required longer reaction times (4 h, TON: 16400, TOF: 4100).