The ability to understand and predict reactivity is essential for the development of new reactions. In the context of Ni-catalyzed C(sp)-O functionalization, we have developed a unique strategy employing activated cyclopropanols to aid the design and optimization of a redox-active leaving group for C(sp)-O arylation. In this chemistry, the cyclopropane ring acts as a reporter of leaving-group reactivity, since the ring-opened product is obtained under polar (2e) conditions, and the ring-closed product is obtained under radical (1e) conditions. Mechanistic studies demonstrate that the optimal leaving group is redox-active and are consistent with a Ni(I)/Ni(III) catalytic cycle. The optimized reaction conditions are also used to synthesize a number of arylcyclopropanes, which are valuable pharmaceutical motifs.
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http://dx.doi.org/10.1021/jacs.0c06904 | DOI Listing |
J Am Chem Soc
December 2024
State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China.
Catalytic asymmetric transformation of donor-acceptor cyclopropanes (DACs) has been proven to be a highly valuable and robust strategy to construct diverse types of enantioenriched molecules. However, the use of 1,1,2,2-tetrasubstituted DACs to form products bearing quaternary stereocenters remains a long-term unsolved challenge. Here, we report the copper-catalyzed asymmetric aminative ring opening of tetrasubstituted alkynyl DACs that delivers a myriad of α-tertiary amines with high levels of enantioselectivities.
View Article and Find Full Text PDFAIDS Res Ther
December 2024
Mbeya College of Health and Allied Sciences, University of Dar es Salaam, Mbeya, Tanzania.
Background: The World Health Organization recommends dolutegravir-based antiretroviral therapy (ART) as the preferred first-line regimen for HIV treatment. This retrospective cohort study evaluated the long-term virologic outcomes and safety of transitioning from an efavirenz-based regimen (tenofovir, lamivudine, efavirenz [TLE]) to a dolutegravir-based regimen (tenofovir, lamivudine, dolutegravir [TLD]) among adult HIV participants in Mbeya, Tanzania.
Methods: Medical records of 250 adult HIV participants who transitioned from TLE to TLD at Mbeya Zonal Referral Hospital were reviewed from August 2022 to December 2022.
Chemistry
December 2024
Universiteit Utrecht, Chemistry, Universiteitsweg 99, 3584CG, Utrecht, NETHERLANDS, KINGDOM OF THE.
Nickelacyclobutanes are reactive intermediates in catalytic cycles involving cyclopropanation and insertion reactions. The stoichiometric study of these intermediates has shown that their reactivity is highly influenced by the coordination environment of the nickel center. A pentacoordinated nickelacyclobutane embedded in a diphosphine pincer ligand has been shown to selectively undergo various reactions with exogenous ligands, including [2+2] cycloreversion and carbene transfer to an isocyanide.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Complesso Universitario di Monserrato, 09042, Monserrato (Cagliari), Italy.
The continuous flow telescoped synthesis of 1,1-cyclopropane aminoketones was achieved by optimizing the photocyclization of 1,2-diketones to 2-hydroxycylobutanones (HCBs) and their reaction with aryl- and alkylamines, tandem condensation C4-C3-ring contraction reaction. With the achieved operational conditions, we were able to obtain a library of cyclopropylamines with good chemical yields, high productivity, and short residence times.
View Article and Find Full Text PDFOrg Lett
December 2024
School of Chemistry, Dalian University of Technology, Dalian 116024, P. R. China.
An efficient palladium-catalyzed -allylic alkylation of pyrazoles and unactivated vinylcyclopropanes is demonstrated, affording various -alkyl pyrazoles in ≤99% yield. This protocol displays high atom economy, a broad range of substrates, and excellent regioselectivity and stereoselectivity. Late-stage modification of bioactive molecules, scaled-up reaction, and divergent derivatization documented the practicability of this methodology.
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