The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Olefin metathesis catalyzed by transition‐metal‐carbene complexes is the most powerful and important carbon‐carbon bond‐forming reactions in modern synthetic organic chemistry. Metathesis transformations, including cross‐metathesis (CM), ring‐closing metathesis (RCM), enyne metathesis, alkyne metathesis, and ring‐opening metathesis polymerization (ROMP), have gained prominence due to the high thermal...
This chapter focuses on cross‐metathesis applications and surveys the literature between 2003 and 2013, highlighting examples from more than 480 papers. After a brief historical overview of cross‐metathesis reactions using well‐defined molybdenum and ruthenium catalysts, olefin functionalization reactions are presented by the group on the smaller or more readily available coupling partner. Functional...
Olefin metathesis (OM) is one of the most versatile methods used to create carbon‐carbon bonds in molecules. The synthetic strategies that it offers have enabled the construction of biologically active natural products. OM is exploited in various ways in chemical biology. Advances in aqueous metathesis, including the development of water‐soluble metathesis catalysts and use of organic co‐solvents...
Ruthenium alkylidenes are widely known to be chemoselective olefin metathesis catalysts and have also been recognized as catalytic precursors for other reactions, such as olefin isomerizations, hydrogenations, oxidations, cyclizations, cycloadditions, rearrangements, cyclopropanations, and others. Since ruthenium alkylidene complexes can be modified to catalyze hydrogenation reactions, only one precatalyst...
Enyne metathesis is one of the major classes of metathesis that redistributes the π systems of an alkene and an alkyne to form a 1,3‐diene. One of the inherent selectivity problems in enyne metathesis originates from the two possible addition modes of a metal alkylidene to alkynes, which ultimately leads to distinct 1,3‐dienes, usually called endo and exo products in enyne ring‐closing metathesis...
Tremendous advances in the field of alkyne metathesis have been recorded over the last decade. The development of molybdenum alkylidyne complexes endowed with silanolate ligands allowed several problems of traditional alkyne metathesis to be solved at once. As occurs in the molybdenum series, alternation of the ancillary ligands about the high‐valent tungsten center imparts significant changes in...
This chapter covers the advances made since 2003 in the development of catalysts that can control the stereochemical outcome of olefin metathesis reactions. Various enantioselective processes, such as enantioselective ring‐opening/cross‐metathesis (EROCM) and enantioselective ring‐closing metathesis (ERCM), promoted by chiral Mo or Ru complexes are discussed. A more recent development has been the...
Chapter 8 consists of two vignettes, each providing personal accounts of the development of ring‐closing metathesis (RCM) approaches to the synthesis of natural products. In Vignette 1, Vanderwal describes how the structure of echinopines A and B inspired the discovery of an allylsilane RCM/electrophilic desilylation methodology for constructing carbocyclic rings with exocyclic alkenes. The implementation...
The chapter describes the achievements in the area of metathesis transformations of silicon‐containing olefins catalyzed by well‐defined alkylidene complexes, published after 2002. The group of reactions discussed in the chapter includes homo and cross‐metathesis, ring‐closing metathesis, acyclic diene metathesis (ADMET) and ring‐opening metathesis polymerization (ROMP). Moreover, silylative cross...
This chapter focuses on the development of ring‐closing metathesis processes as applied to a number of developmental and commercial active pharmaceutical ingredients (APIs). After analyzing the process development of each drug, specifically focusing on the problems encountered by the chemists, the chapter tries to provide a framework that can be used by practitioners of this reaction to develop it...
Diversity‐oriented synthesis (DOS) aims to generate stereochemically and skeletally diverse small molecules of increased structural complexity (as compared to traditional compound collections) in a rapid and efficient manner. In this regard, metathesis has seen widespread use in DOS as a robust and reliable synthetic method for accessing molecular complexity and structural diversity. Highlights include...
Of the numerous commercial opportunities for olefin metathesis, this chapter focuses on renewable feedstock processes, hydrogenated nitrile butadiene rubber (HNBR) products, candidates for pharmaceuticals, and ROMP‐derived functionalized oligomers. Among the renewable feedstock processes was the startup of a 180 k MT per year bio‐refinery plant in Gresik, Indonesia. Lanxess' Therban™ products, consisting...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.