N-Heterocyclic carbene adducts of cyclopalladated ferrocenylpyridine: Synthesis, structural characterization and reusable catalytic system for Suzuki and amination of aryl chlorides in poly(ethylene glycol-400)

Abstract

Two air-stable carbene adducts of cyclopalladated ferrocenylpyridine 1–2 have been synthesized and characterized by elemental analysis, IR, ESI-MS, 1H and 13C NMR. Additionally, their detailed structures have been determined by single-crystal X-ray analysis. The use of these complexes as catalysts for the Suzuki and Buchwald–Hartwig amination of aryl chlorides was examined. Compound 2 was found to be very efficient for these reactions. Typically, using 0.5–1mol% of catalyst in the presence of 3equivalents of KtOBu as base in PEG-400 [poly(ethylene glycol-400)] at 120°C provided coupling products in excellent yields. Moreover, the 2/PEG-400 system could be recycled and reused three times.