New olefin metathesis catalysts bearing polyether clamp in N-heterocyclic carbenes ligands

Synthesis of new type of the Hoveyda–Grubbs catalysts containing modified N-heterocyclic carbene ligands is described herein. New catalysts bear different in size polyether clamp embracing N,N′-2,4-dimethylphenyl substituents in N-heterocyclic carbene. New complexes were tested in model RCM, enyne and CM reactions. They showed comparable activity to that of commercially available Grubbs second generation and Hoveyda–Grubbs second generation complexes. Complex with larger polyether clamp proved Z-stereoselective in a macrocycle formation and yielded more Z isomers than commercial complexes in CM reactions. The catalysts are stable and easy to purify.

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