A new class of chiral cyclopentadienyl rhodium(I) complexes (CpRh ) bearing C -symmetric chiral bridged-ring-fused Cp ligands was prepared. The complexes were successfully applied to the asymmetric C-H activation reaction of N-methoxybenzamides with quinones, affording a series of chiral hydrophenanthridinones in up to 82 % yield with up to 99 % ee. Interestingly, structure analysis reveals that the side wall of the optimal chiral CpRh catalyst is vertically more extended, horizontally less extended, and closer to the metal center in comparison with the classic binaphthyl and spirobiindanyl CpRh complexes, and may thus account for its superior catalytic performance.
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http://dx.doi.org/10.1002/anie.202010489 | DOI Listing |
ACS Catal
August 2024
Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Low-valent cobalt complexes can promote intramolecular (3 + 2) cycloadditions of alkyne-tethered cyclopropenes to provide bicyclic systems containing highly substituted cyclopentadienyl moieties with electronically diverse functional groups. The adducts can be easily transformed into new types of CpRh(III) and CpIr(III) complexes, which show catalytic activity in several relevant transformations. Preliminary computational (DFT) and experimental studies provide relevant information on the mechanistic peculiarities of the cobalt-catalyzed process and allow us to rationalize its advantages over the homologous rhodium-promoted reaction.
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February 2024
Department of Physics and Astronomy, Uppsala University 751 20 Uppsala Sweden
Photochemically prepared transition-metal complexes are known to be effective at cleaving the strong C-H bonds of organic molecules in room temperature solutions. There is also ample theoretical evidence that the two-way, metal to ligand (MLCT) and ligand to metal (LMCT), charge-transfer between an incoming alkane C-H group and the transition metal is the decisive interaction in the C-H activation reaction. What is missing, however, are experimental methods to directly probe these interactions in order to reveal what determines reactivity of intermediates and the rate of the reaction.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2022
Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125, Berlin, Germany.
We report the density functional theory (DFT) guided discovery of ethynyl-triazolyl-phosphinates (ETPs) as a new class of electrophilic warheads for cysteine selective bioconjugation. By using Cu -catalysed azide alkyne cycloaddition (CuAAC) in aqueous buffer, we were able to access a variety of functional electrophilic building blocks, including proteins, from diethynyl-phosphinate. ETP-reagents were used to obtain fluorescent peptide-conjugates for receptor labelling on live cells and a stable and a biologically active antibody-drug-conjugate.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
June 2022
Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510006, P. R. China.
Chiral half-sandwich cyclopentadienyl rhodium(III) (CpRh ) complexes are powerful catalysts for promoting asymmetric C-H activation reactions. Their preparation normally involved linking or embedding the Cp motif to or into a certain chiral backbone to forge the so-called chiral Cp ligand. However, preparation of a planar-chiral CpRh catalyst bearing a non-chiral Cp ligand remains a formidable challenge and is rarely reported.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2021
State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, 345 Lingling Lu, Shanghai, 200032, China.
Chiral cyclopentadienyl rhodium (CpRh) complex-catalyzed asymmetric C-H functionalization reactions have witnessed a significant progress in organic synthesis. In sharp contrast, the reported chiral Cp ligands are limited to C-linked Cp and are often synthetically challenging. To address these issues, we have developed a novel class of tunable chiral cyclopentadienyl ligands bearing oxygen linkers, which were efficient catalysts for C-H arylation of benzo[h]quinolines with 1-diazonaphthoquinones, affording axially chiral heterobiaryls in excellent yields and enantioselectivity (up to 99 % yield, 98.
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