Flow-Based, Cerium Oxide Enhanced, Low-Level Palladium Sonogashira and Heck Coupling Reactions by Perovskite Catalysts

Claudio Battilocchio¹, Benjamin N. Bhawal¹, Rajeev Chorghade¹, Benjamin J. Deadman¹, Joel M. Hawkins², Steven V. Ley¹

• ¹ Innovative Technology Centre, Department of Chemistry, University of Cambridge, UK
• ² Pfizer Worldwide Research & Development, Groton, USA

A flow chemistry procedure for Sonogashira and Heck cross-coupling reactions using a low-level palladium perovskite catalyst (LaFe_0.95Pd_0.05O₃) deposited on cerium oxide is reported. The catalyst was generated in situ at high temperature using a flow platform. The system could be applied to a wide range of functionalised substrates, allowing clean and fast delivery of the products within a few minutes (10–30 min), after scavenging with thiourea polymer (QP-TU) and sulfonic acid resin (QP-SA). The use of an in-line evaporator/solvent switching device allowed us to recover the solvent and transport the material into the following stage. The catalyst could be continuously used for at least 24 h, without any noticeable decrease in the catalytic efficiency. In one example the system was scaled to deliver 10 mmol of product.

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