Grubbs/Herrmann metathesis catalyst

Fig.1 Well-defined metathesis initiators. Schrock catalyst (A, R = Me, Ph, R = CMes, CMe(CF3)2), Grubbs-catalyst (B), Grubbs-Herrmann catalyst (C), Grubbs-Hoveyda catalyst (D, R " = H, NO2)...

Several catalysts for ring-closing metathesis are now known. Prominent examples are shown in Scheme 1 the molybdenum carbene complex 8, introduced by Schrock et al. [4], methyltri-oxorhenium 9, discovered by Herrmann et al. [5] and the ruthenium carbene complex 10, developed by Grubbs et al. [6]... 

With the work by Grubbs et al. [27] and Herrmann et al. [28], the use of ruthenium carbene complexes as homogeneous catalysts for the ROMP (Ring-Opening Metathesis Polymerization) of olefins was estabhshed (see Section 2.4.4.3). The development of catalysts that can catalyze hving polymerization in water was an important goal to achieve, especially for applications in biomedicine. In this context, two water-soluble ruthenium carbene complexes (3 and 4) have been reported that act as initiators for the living polymerization of water-soluble monomers in a quick and quantitative manner [29]. 

Over the last decade, our group has shown in multiple instances that monometallic Ru catalysts active in olefin metathesis could also be turned into efficient promoters for atom transfer radical reactions with only minor ligand tuning. Such a dual activity was evidenced, among others, for Grubbs catalyst Ru-arene complex 3, Herrmann bis-NHC or mixed-... 

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