Recyclable Hybrid Silica‐Based Catalysts Derived from Pd–NHC Complexes for Suzuki, Heck and Sonogashira Reactions

• DOI: 10.1002/ejoc.201200205
• Publication Date: 2012-05-23T12:30:06Z
• Authors: Guadalupe Borja; Amàlia Monge‐Marcet; Roser Pleixats; Teodor Parella; Xavier Cattoën; Michel Wong Chi Man
• Keywords: Sol-gel processes; Heterogeneous catalysis; Supported catalysts; [CHIM.MATE]Chemical Sciences/Material chemistry; 01 natural sciences; 0104 chemical sciences; 12. Responsible consumption; Green chemistry; Carbenes; Cross-coupling; C-C coupling; Palladium

AbstractTwo silylated Pd–NHC complexes were immobilized on hybrid silicas by sol‐gel cocondensation with tetraethyl orthosilicate (TEOS) and performed well as recyclable catalysts towards the Heck, Suzuki, and Sonogashira coupling reactions. Remarkable conversion and recyclability were achieved in the Suzuki reaction with a challenging aryl chloride. No side products and no undesired homocoupling were observed in Suzuki or Heck reactions, which facilitates the final purification step for the cross‐coupling products. High turnover numbers and turnover frequencies were found for copper‐ and phosphane‐free Sonogashira reaction between p‐bromoacetophenone and phenylacetylene.