Biomimetic modularization and function-oriented synthesis of structurally diversified natural product-like macrocycles in a step-economical fashion is highly desirable. Inspired by marine furanocembranoids, herein, we synthesize diverse alkenes substituted furan-embedded macrolactams via a modular biomimetic assembly strategy. The success of this assembly is the development of crucial Pd-catalyzed carbene coupling between ene-yne-ketones as donor/donor carbene precursors and unactivated Csp‒H bonds which represents a great challenge in organic synthesis. Notably, this method not only obviates the use of unstable, explosive, and toxic diazo compounds, but also can be amenable to allenyl ketones carbene precursors. DFT calculations demonstrate that a formal 1,4-Pd shift could be involved in the mechanism. Moreover, the collected furanocembranoids-like macrolactams show significant anti-inflammatory activities against TNF-α, IL-6, and IL-1β and the cytotoxicity is comparable to Dexamethasone.
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http://dx.doi.org/10.1038/s41467-021-21484-x | DOI Listing |
Chemistry
December 2024
Université de Liège: Universite de Liege, Laboratory of Organometallic Chemistry and Homogeneous Catalysis, Institut de chimie B6a, Sart-Tilman, 4000, Liege, BELGIUM.
Thirteen imidazolium iodides bearing benzyl, mesityl, or 2,6-diiso-propyl-phenyl substituents on their nitrogen atoms, and C1 to C4 alkyl chains on their C2 carbon atom were readily deuterated with D2O as a cheap and non-toxic deuterium source in the presence of Cs2CO3, a weak, innocuous, inorganic base. The isotopic exchange proceeded quickly and efficiently under mild, aerobic conditions to afford a range of aNHC and NHO precursors regioselectively labeled on their C2α exocyclic position and/or C4=C5 heterocyclic backbone. A "carbene-free" mechanism was postulated, in which the carbonate anion acts as a catalyst to activate an exocyclic, acidic C-H bond and ease a deuterium transfer from D2O to the imidazolium salt in a concerted fashion.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Shandong University, Chemistry and Chemical Engineering, Shanda South Road 27, 250100, Jinan, CHINA.
Catalytic transformation of carbene species constitutes a fundamental part in organic synthesis, and the research in this direction has been dominated by transition metals while organic catalysts are difficult to mimic such transition-metal-like reactivity. It would significantly advance carbene chemistry if organic catalysts enable achieving classical metal-carbene approaches otherwise unrealizable reactions. Herein, we report that chalcogen bonding catalysis can solve reactivity problem to achieve an elusive Buchner ring expansion of aryl ketones appending a cyclopropene moiety as carbene precursor.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
The ultraviolet (UV) photodissociation of pyruvic acid through the absorption of solar actinic flux generates methylhydroxycarbene (MHC) in the atmosphere. It is recognized that isolated MHC can undergo unimolecular isomerization to form acetaldehyde and vinyl alcohol. However, the rates and mechanism for its possible bimolecular reactions with atmospheric constituents, which can occur in parallel with its unimolecular reaction, is not well understood.
View Article and Find Full Text PDFAcc Chem Res
December 2024
Department of Chemistry, Northeast Normal University, Changchun 130024, China.
ConspectusIn the past decade, single-atom skeletal editing, which involves the precise insertion, deletion, or exchange of single atoms in the core skeleton of a molecule, has emerged as a promising synthetic strategy for the rapid construction or diversification of complex molecules without laborious synthetic processes. Among them, carbene-initiated skeletal editing is particularly appealing due to the ready availability and diverse reactivities of carbene species. The initial endeavors to modify the core skeleton of heteroarenes through carbon-atom insertion could date back to 1881, when Ciamician and Denstedt described the conversion of pyrroles to pyridines by trapping haloform-derived free carbene.
View Article and Find Full Text PDFRSC Adv
December 2024
Natural and Medical Sciences Research Center (NMSRC), University of Nizwa Nizwa 616 Sulanate of Oman.
Diazo compounds are known to be good coupling partners in the synthesis of heterocycles, carbocycles and functionalized molecules a rhodium carbene-based strategy. Many heterocyclic and carbocyclic compounds, including isoquinolones and isocoumarins, quinoxalines, indoles, pyrrones, benzothazines, enaminones, benzenes and seven-membered rings, can be constructed using this rhodium-catalyzed system. The reaction mechanism involves C-H activation, carbene insertion and an annulation/functionalization sequence.
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