Chemoselective olefin metathesis transformations mediated by ruthenium complexes

Abstract

Over the past decade, ruthenium-mediated metathesis transformations, including polymerization reactions, cross-metathesis, ring-closing metathesis, enyne metathesis, ring-rearrangement metathesis, and also tandem processes, represent one of the most studied families of organic reactions. This has translated into the development of a large number of structurally diverse catalysts. Whereas most of these investigations are focused on determining catalytic performance, only rare examples of studies dealing with chemoselectivity have been reported to date. Usually, variations are observed in product conversions but rarely in product distributions. In this critical review, we provide an overview of the stereochemistry of newly formed C=C bonds either in ring-closing or cross-metathesis as a function of the catalyst structure. A discussion of disparities encountered in macrocyclisation reactions leading (or not) to the formation of dimeric products is also presented. Since distinctive metathesis products could be isolated as a function of the ligand borne by the ruthenium centre--phosphine or N-heterocyclic carbene in the dissymetrization of trienes, enyne metathesis and ring rearrangements, these topics are also discussed (72 references).

5.27 Ene–Yne Metathesis

“…The indenylidene catalyst 6, sometimes called the Umicore catalyst, has also been used for EYM with performance comparable to that of the Grubbs complex 2. [28][29][30] In catalysis, activity refers to a combination of catalyst attributes including favorable initiation rates and long propagation lifetime (catalyst longevity). Though the phosphine-free initiators are more active, they are not necessary for most applications.…”

Direct synthesis of ruthenium catalyst precursors from ammonium (oxide) chloride salts via hydrothermal reaction

“…Ruthenium chemistry has continued to gain attention in recent years owing to catalytic applications in various technologies [1] including cyclopropanation [2], hydrogenation of carbonyls [3], oxidation [4], and olefin metathesis [5][6][7][8][9]. As a result, we became interested in developing synthetic routes to chemical precursors directly from the ruthenium salts that are generated during the refining and recycling of ruthenium.…”

Synthesis of Aromatic Heterocycles Using Ring-Closing Metathesis

“…Ring-closing metathesis (RCM) is a marvelous tool and has attracted interest as a powerful method for formation of a seemingly limitless array of ring systems and a number of reviews have been published to date (00AGE3012, 05AGE4490, 05CTMC1521, 10CSR3305,10MI1,11CC6505,12CSR4389,13AGE9001,14MI1,15TL5261). Its popularity can be largely attributed to the commercial availability of effective catalysts that are tolerant of a wide range of functional groups (09CR3708, 10CR1746, 10CR4865, 16AGE3552).…”