The scope of the Giese reaction is expanded using readily available alkyl tosylates as substrates and nucleophilic cobalt(i) catalysts under visible-light irradiation. The reaction proceeds preferentially with less bulky primary alkyl tosylates. This unique reactivity enables the regio-selective Giese reaction of polyol derivatives.
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http://dx.doi.org/10.1039/d0ra10739e | DOI Listing |
Beilstein J Org Chem
December 2024
Department of Chemical and Geological Sciences, University of Cagliari, S.S. 554, bivio per Sestu, 09042 Monserrato (CA), Italy.
The rising popularity of bioconjugate therapeutics has led to growing interest in late-stage functionalization (LSF) of peptide scaffolds. α,β-Unsaturated amino acids like dehydroalanine (Dha) derivatives have emerged as particularly useful structures, as the electron-deficient olefin moiety can engage in late-stage functionalization reactions, like a Giese-type reaction. Cheap and widely available building blocks like organohalides can be converted into alkyl radicals by means of photoinduced silane-mediated halogen-atom transfer (XAT) to offer a mild and straightforward methodology of alkylation.
View Article and Find Full Text PDFOrg Lett
December 2024
National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, China.
We have developed a glycosyl radical-based synthesis of -alkyl glycosides through a deoxygenative Giese addition-reduction-cyclization cascade, in which readily available 1-hydroxy carbohydrates serve as precursors for glycosyl radicals and aryl alkenes function as radical acceptors. This reaction not only provides an effective method for accessing a previously underexplored class of functionalized cyclopropanes but also enhances the application of Giese addition in the synthesis of -alkyl glycosides by derivatizing the radical intermediate generated through polar cyclization to yield a cyclopropane.
View Article and Find Full Text PDFACS Omega
November 2024
Departamento de Química, Instituto de Investigación en Química de la Universidad de La Rioja (IQUR), Universidad de La Rioja, C/Madre de Dios, 53, Logroño, La Rioja 26006, Spain.
ChemistryOpen
November 2024
Institute of General and Ecological Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego 116, 90-924, Łódź, Poland.
Electrochemically induced, decarboxylative functionalization of chromone-3-carboxylic acids by N-hydroxyphthalimide esters as alkyl radical precursors was studied. Electrochemical protocol offers a sustainable and green approach, obviating the need for catalysts, relying on the direct reduction of NHPI esters using electric current. Developed protocol provides a straightforward route to the synthesis of diverse molecules with potential biological activity.
View Article and Find Full Text PDFJ Org Chem
November 2024
Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, Scotland, United Kingdom.
Previous light-mediated approaches to the direct decarboxylative Giese aroylation reaction have mainly relied on the use of a photocatalyst and a reductive quenching pathway. By exploiting a mechanistically distinct oxidative protocol, we have successfully developed a photocatalyst-free, light-mediated direct Giese aroylation methodology.
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