22921-58-0Relevant articles and documents
Metathesis and Decomposition of Fischer Carbenes of Cyclometalated Z-Selective Ruthenium Metathesis Catalysts
Ahmed, Tonia S.,Grandner, Jessica M.,Taylor, Buck L. H.,Herbert, Myles B.,Houk,Grubbs, Robert H.
, p. 2212 - 2216 (2018)
The addition of vinyl ethers to Z-selective, cyclometalated ruthenium metathesis catalysts generates Fischer carbene complexes. Although Fischer carbenes are usually thought to be metathesis inactive, we show that Fischer carbenes are metathesis active under certain circumstances. These species were found to decompose facilely to Ru hydride complexes, as identified by both experiment and computation. Since vinyl ethers are often used to quench metathesis reactions implementing Ru-based metathesis catalysts, their decomposition to hydrides can have a deleterious effect on the desired stereochemistry of the olefin product.
Ruthenabenzene: A Robust Precatalyst
Gupta, Saswata,Su, Siyuan,Zhang, Yu,Liu, Peng,Wink, Donald J.,Lee, Daesung
supporting information, p. 7490 - 7500 (2021/05/26)
Metallaaromatics constitute a unique class of aromatic compounds where one or more transition metal elements are incorporated into the aromatic system, the parent of which is metallabenzene. One of the main concerns about metallabenzenes generally deals with the structural characterization related to their relative aromaticity compared to the carbon archetype. Transition metal-containing metallabenzenes are also implicated in certain catalytic processes such as alkyne metathesis polymerization; however, these transition metal-based metallaaromatic compounds have not been developed as a catalyst. Herein, we describe an effective strategy to generate diverse arrays of ruthenabenzenes and demonstrated them as an aromatic equivalent of the Grubbs-type ruthenium alkylidene catalysts. These ruthenabenzenes can be prepared via an enyne metathesis and metallotropic [1,3]-shift cascade process to form alkyne-chelated ruthenium alkylidene intermediates followed by spontaneous cycloaromatization. The aromatic nature of these complexes was confirmed by spectroscopic and X-ray crystallographic data, and the mechanistic pathways for the cycloaromatization process were studied by DFT calculations. These ruthenabenzenes display robust catalytic activity for metathesis and other transformations, which illustrates that metallabenzenes are not only compounds of structural and theoretical interests but also are a novel platform for new catalyst development.
Chiral Lithium Amido Zincates for Enantioselective 1,2-Additions: Auto-assembling Reagents Involving a Fully Recyclable Ligand
Rouen, Mathieu,Chaumont, Pauline,Barozzino-Consiglio, Gabriella,Maddaluno, Jacques,Harrison-Marchand, Anne
supporting information, p. 9238 - 9242 (2018/06/04)
A methodology consisting in carrying out enantioselective nucleophilic 1,2-additions (ee values up to 97 %) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto-assemble when mixing, in a 1:1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully recoverable thanks to a simple acid–base wash, allowing being recycled and re-use without loss of stereochemical information.
