By making use of a direct C-H activation strategy, an efficient osmium(II)-catalyzed redox-neutral [4 + 2] annulation of -methoxybenzamides with alkynes has been accomplished. Computational and experimental studies revealed that such transformation leading to the synthesis of the isoquinolone core might follow an Os(II)-Os(IV)-Os(II) catalytic pathway, in which an unusual HOAc-assisted oxidative addition of osmium(II) into the N-O bond to generate the osmium(IV) species was involved as one of the key transition states. Further exploration of divergent C-H activation reaction modes enabled by the osmium(II) catalyst has also been exemplified for one-pot assembly of other either linear or cyclic products.
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http://dx.doi.org/10.1021/acs.orglett.9b03827 | DOI Listing |
Dalton Trans
January 2025
Department of Chemistry, Indian Institute of Technology Jodhpur, Karwar, Jodhpur, 342037, Rajasthan, India.
The synthesis of a novel phosphine-based pincer chromium(II) complex CrCl(PONN) (Cr-1) is reported in this study. The complex exhibited promising catalytic performance in C-C and C-N bond formation using the borrowing hydrogen methodology. Cr-1 catalyzed the α-alkylation of ketones using primary alcohols as alkyl surrogates in the presence of catalytic amount of a base.
View Article and Find Full Text PDFChem Sci
December 2024
School of Chemistry and Chemical Engineering, Hainan University Haikou 570228 China
J Am Chem Soc
November 2024
The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.
Electrosynthesis has emerged as a versatile and sustainable tool in organic chemistry, offering an efficient pathway for the construction of complex molecular architectures under mild and environmentally benign conditions. Traditional electrochemical approaches, however, predominantly rely on either anodic oxidation or cathodic reduction, limiting their capacity to achieve redox-neutral transformations using a single electrode. In this work, we introduce a linear paired electrolysis strategy that circumvents these limitations, enabling a redox-neutral (3 + 2) annulation of benzofuran with vinyldiazo compounds.
View Article and Find Full Text PDFJ Org Chem
November 2024
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
In water, Ru-catalyzed annulation of -chlorobenzamides with unsymmetrical internal alkynes bearing aryl, hydroxy, ester, and sulfonyl functionalities has been accomplished to afford isoquinolone scaffolds under external oxidant-free conditions at room temperature. Use of water as reaction medium, redox-neutral conditions, regioselectivity, and substrate scope are important practical features.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
Tryptophan and its non-canonical variants play critical roles in pharmaceutical molecules and various enzymes. Facile access to this privileged class of amino acids from readily available building blocks remains a long-standing challenge. Here, we report a regioselective synthesis of non-canonical tryptophans bearing C4-C7 substituents via Rh-catalyzed annulation between structurally diverse tert-butyloxycarbonyl (Boc)-protected anilines and alkynyl chlorides readily prepared from amino acid building blocks.
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