Nitro and Other Electron Withdrawing Group Activated Ruthenium Catalysts for Olefin Metathesis Reactions

Abstract

From the Contents 1. Olefin Metathesis Reaction and Established Catalysts Types 13739 2. The EWG-Activation Concept, Early Observations, and Consequences 13740 3. Synthesis of Advanced Biologically Active and Natural Compounds by Utilizing EWG-Activated Catalysts 13741 4. Applications in the Synthesis of Active Pharmaceutic Ingredients 13748 5. Production of Specialty Chemicals and Commodities, as well as Applications in Materials Science 13750 6. Practical Considerations, Outlook, and Perspectives 13752 Scheme 1. Basic types of olefin metathesis. RCM = ring-closing metathesis;ROM = ring-opening metathesis;ADMET = acyclic diene metathesis;ROMP = ring-opening metathesis polymerization;C M= crossmetathesis.

Light‐Driven gem Hydrogenation: An Orthogonal Entry into “Second‐Generation” Ruthenium Carbene Catalysts for Olefin Metathesis

“…The other tested iodo‐chelate complexes reacted analogously, even though the yields seem to be dependent on the size and substitution pattern of the NHC ligand, whereas complexes 5 i – k containing sulfur or nitrogen in the chelate ring did not undergo this transformation. This favorable result shows that prototypical “second‐generation” Grubbs‐Hoveyda complexes of type 3 or the corresponding Grela variants ( 3 c ) [32] are now accessible in good to excellent overall yield in only three operations starting from commercial [(η 6 ‐cymene)RuCl 2 ] 2 without the need to resort to phenyldiazomethane or other hazardous reagents. The new approach therefore constitutes an alternative to the use of propargyl alcohols (or chlorides), which enjoy widespread use as carbene sources [10,11,33,34] .…”

Recent Developments in Z‐Selective Olefin Metathesis Reactions by Molybdenum, Tungsten, Ruthenium, and Vanadium Catalysts

“…Olefin metathesis [1–3] has been widely used for synthesis of various organic compounds (especially fine chemicals and pharmaceuticals) [4–11] and advanced polymers [12–22] . These reactions proceed via metalloacyclobutane intermediate after coordination of olefins to the metal‐carbene (alkylidene) species, which play an important role in this catalysis (Scheme 1).…”

“…In this reviewing article, reports on Z selective olefin metathesis in organic and polymer synthesis using “designed” Z selective catalysts have been summarized [33–51] . It should be better to describe in the introductory that high Z selectivity can also be observed in the olefin metathesis even using ordinary catalysts (shown in Scheme 1), exemplified as ROMP, [52] RCM, [9,11,53] and in CM [54] . The mechanism for the high cis selectivity in the ROMP could be explained by the syn / anti isomers as well as subsequent coordination of monomers [52] .…”

“…The mechanism for the high cis selectivity in the ROMP could be explained by the syn / anti isomers as well as subsequent coordination of monomers [52] . In RCM, “there have been many examples in Z selective formations of not only small rings (5‐, 6‐, and 7‐membered), but also of macrocycles (14–17 membered)”; [9] some of these were applied for synthesis of important pharmaceuticals (drugs) and natural products by adopting ordinary catalysts [11,53] . These examples were, however, excluded in this reviewing articles to focus on reports for Z selective formation of carbon‐carbon double bonds in olefin metathesis by designed molecular catalysts.…”

Ruthenium Olefin Metathesis Catalysts Featuring N-Heterocyclic Carbene Ligands Tagged with Isonicotinic and 4-(Dimethylamino)benzoic Acid Rests: Evaluation of a Modular Synthetic Strategy

“…Its privileged role would not be possible without the development of well-defined ruthenium complexes, especially stable and easily adjustable Grubbs, Hoveyda-Grubbs, and indenylidene type second-generation catalysts possessing N-heterocyclic carbenes (NHC) (Figure 1, top) [3,4]. Besides improving the control over the (E)/(Z) selectivity [5,6] and substrate scope of olefin metathesis reactions themselves [7][8][9][10][11], considerable process-related efforts have been undertaken to increase their attractiveness for industrial applications with respect to catalyst activity and stability, possibility of its recycling, and minimizing the level of toxic and polluting metal contaminants in the final products [12][13][14]. An attractive solution for the latter issue is the heterogenization of the catalyst on solid (or liquid) supports.…”