A DFT mechanistic study reveals that nitrenium ion-modified Hoveyda-like complexes are good candidates for latent metathesis catalysts, while boron-modified systems are candidates for very fast metathesis catalysts.
The activation of latent ruthenium complexes containing two unsymmetrical NHCs by copper and gold transmetalation leads to impressive initiation rates in olefin metathesis.
This feature article discusses the synthesis of new asymmetric Grubbs–Hoveyda II complexes with extended N-heterocyclic carbenes containing a bicyclic camphor-based framework. The new enantiopure complexes can be prepared in a short route from the chiral pool. The extended carbene-based catalyst shows high activity in olefin metathesis reactions. The new complexes exhibited enantioselectivity in an asymmetric ROCM desymmetrization. Depending on the substituents on the nitrogen atoms of the carbenes, the opposite enantiomer was formed in excess.
New second generation ruthenium catalysts bearing unsymmetrical NHCs show different catalytic efficiencies depending on the size of the N-alkyl group (methyl or cyclohexyl) and on the backbone configuration.
Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide
