Heterogeneously Pd/C catalysed procedure for the vinylation of aryl bromides

Heterogeneous Pd/C catalyst was applied to the Suzuki-Miyaura vinylation of various aryl and heteroaryl halides under aerobic and mild reaction conditions [1.0 mmol aryl halide, 1.5 mmol potassium vinyltrifluoroborate, 3.0 mmol K3PO4 center dot H2O, 0.1 mol% Pd/C-(EVO), 1 mL NMP, 100 degrees C, 24 h]. Useful isolated yields (57-73%) were achieved. In some cases, the catalytic system should be tuned to face the reactivity of the aryl halides: while 0.1 mol% Pd/C is sufficient for almost all aryl bromides, 1.0 mol% Pd/C was used for free phenols. The heterogeneous catalyst was proved to be stable upon several catalytic cycles: however, the results showed that this was dependent on addition of the base. Hot-filtration experiment indicates that the activity was mainly due to leached Pd-species, indicating that the Pd/C catalyst acts as a palladium reservoir. (c) 2009 Elsevier B.V. All rights reserved.