The ability of heteroatom stabilized Fischer carbene complexes (FCCs) to participate in multicomponent reactions (MCRs) has become a characteristic of such organometallics, particularly of chromium carbenes. This feature article updates the main results in this field during the last lustrum, highlighting the ability of FCCs for the construction of densely functionalized frameworks, mainly through the successive incorporation of unsaturated moieties (alkynes, CO ligands,…) in a sequential manner. Examples where up to seven components are coupled will be presented.
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http://dx.doi.org/10.1039/c0cc02337j | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Max-Planck-Institut fur Kohlenforschung, Organometallic Chemistry, Kaiser-Wilhelm-Platz 1, 45470, Mülheim/Ruhr, GERMANY.
Ynamides, when reacted with H2 or HBpin in the presence of [Cp*RuCl]4, convert into chiral-at-metal Fischer carbenes by regioselective gem-hydrogenation or gem-hydroboration of the polarized triple bond, respectively. gem-Hydroboration concomitantly affords a carbogenic borylated stereocenter adjacent to the ruthenium carbene unit, the configuration of which can be controlled using an Evans auxiliary. These are the first examples of asymmetric gem-addition reactions to alkynes known in the literature; representative pianostool ruthenium carbene complexes formed by this unconventional route were characterized by crystallographic and spectroscopic means.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg. Germany.
The presence of inherent electronic unsaturation in aluminum predominantly results in the formation of aluminum clusters, with very few examples of compounds containing discrete chains of aluminum atoms in existence. In this work, we present the successful synthesis and structural authentication of a highly unusual trialane species with a near-linear chain of three Al atoms, alongside a carbene-stabilized aluminyl anion ([LAlR]), an alternative product produced by varying the reaction conditions. Quantum-chemical calculations have been applied to elucidate the electronic structure and bonding of these novel compounds.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Department School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332, United States.
Fischer carbenes have recently found great utility in the construction of degradable metathesis materials, but investigations have been limited to oxygen-containing enol ether monomers. Here, the ring-opening metathesis polymerization of 1,2-dihydroazetes is reported. The polymerization proceeds regioselectively, and the resulting molecular weights are targetable by adjusting the Grubbs initiator loading.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-0032, Japan.
While ring-closing metathesis (RCM) is a powerful method for constructing medium and large cyclic alkenes, its application to the synthesis of heterocycles faces considerable limitations. For instance, RCM of divinyloxyalkanes does not proceed under the conventional conditions of RCM. The challenge lies in the formation of stable Fischer-type carbene intermediates with heteroatom(s) bound to the carbene carbon, impeding subsequent metathesis.
View Article and Find Full Text PDFChemistry
January 2025
Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße 7, 28359, Bremen, Germany.
The synthesis, characterization and reactivity of the diferrocenylphosphenium ion [FcP] was extended to the heavier diferrocenylpnictogenium ions, [FcE] (E=As, Sb, Bi). The lighter diferrocenylnitrenium ion, [FcN], was detected by mass spectrometry, but could not be isolated. The molecular structures of [FcE] (E=P, As, Sb, Bi) reveal intramolecular coordination of the iron atoms, which counterbalance the electron deficiency of the pnictogens without affecting the strong Lewis acidities, which were determined according to the method of Gutmann and Beckett.
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