Cationic gold vinyl carbene/allylic cation complexes of the form ()-[(L)AuC(H)C(H)CAr] OTf {L = IPr, Ar = Ph [()-], L = IPr, Ar = 4-CHOMe [()-], L = P(-Bu) -biphenyl, Ar = 4-CHOMe [()-]} were generated in solution Lewis acid-mediated ionization of the corresponding gold (γ-methoxy)vinyl complexes ()-(L)AuC(H)C(H)C(OMe)Ar at or below -95 °C. Complexes ()- and ()- were fully characterized in solution employing multinuclear NMR spectroscopy, which established the predominant contribution of the aurated allylic cation resonance structure and the significant distribution of positive charge into the γ-anisyl rings. Complex ()- reacted rapidly at -95 °C with neutral two-electron, hydride, and oxygen atom donors exclusively at the C1 position of the vinyl carbene moiety and with -methoxystyrene to form the corresponding vinylcyclopropane. In the absence of nucleophile ()- decomposed predominantly intermolecular carbene dimerization whereas formation of 1-aryl-5-methoxy indene upon ionization of ()-(IPr)AuC(H)C(H)C(OMe)(4-CHOMe) [()-] implicated an intramolecular Friedel-Crafts or electrocyclic Nazarov pathway for the decomposition of the unobserved vinyl carbene complex ()-[(IPr)AuC(H)C(H)C(4-CHOMe)] OTf [()-].
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6585879 | PMC |
| http://dx.doi.org/10.1039/c9sc01574d | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Tropospheric Fate of Methylhydroxycarbene and the Ability of a Single Water Molecule to Efficiently Promote Its Isomerization into Acetaldehyde.
J Am Chem Soc
January 2025
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 PDFSynthesis of Arenesulfenyl Fluorides and Fluorosulfenylation of Alkenes, Alkynes, and α-Diazocarbonyl Compounds.
Angew Chem Int Ed Engl
December 2024
Department of Chemistry and Chemical Biology, Harvard University Cambridge, Massachusetts, 02138, United States.
Sulfenyl fluorides are organic compounds of sulfur in formal oxidation state +2 with the formula R-S-F. Although the chloride, bromide, and iodide analogues have been extensively described in the literature, arenesulfenyl fluorides remain essentially unstudied. These structures have been implicated as putative intermediates in established processes to access polyfluorinated sulfur species; however, definitive and direct evidence of their existence has not been obtained, nor has a systematic understanding of their reactivity.
View Article and Find Full Text PDFRing-Enlargement of in Situ Generated Cyclopropanones by the Reaction with Sulfonium Ylides: One-Pot Synthesis of Cyclobutanones.
Org Lett
November 2024
Institute of Organic Chemistry, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.
In this report, we describe a simple method for the synthesis of 2-aryl-2-vinyl-cyclobutanones through the reaction of in situ generated cyclopropanones and cinnamylsulfonium ylides, representing an example of a formal carbene insertion into these three-membered rings. The cyclobutanones thus obtained are ideal substrates for palladium-catalyzed coupling reactions upon enol triflate formation, thereby providing access to densely functionalized cyclobutenes. A mechanistic proposal for the ring-enlargement is presented based on experimental evidence.
View Article and Find Full Text PDFDFT rationalization of the mechanism and selectivity in a gold-catalyzed oxidative cyclization of diynones with alcohols.
Phys Chem Chem Phys
November 2024
Key Laboratory of Chemical Additives for China National Light Industry, College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, P. R. China.
The mechanism, regioselectivity, and chemoselectivity in a gold-catalyzed oxidative cyclization of diynones with alcohols to give furan-3-carboxylate derivatives were explored by density functional theory (DFT). The obtained results revealed that the first step of the global reaction involves a nucleophilic attack of a pyridine--oxide derivative on the catalyst-ligated diynone, forming a vinyl intermediate that can isomerize to an α,α'-dioxo gold carbene upon the cleavage of the N-O bond. In the second step, a nucleophilic addition is also completed pyridine--oxide instead of an alcohol proposed in the experiment.
View Article and Find Full Text PDFA Photochemical Strategy towards Michael Addition Reactions of Cyclopropenes.
Angew Chem Int Ed Engl
November 2024
Department of Chemistry, Indian Institute of Technology Jammu, Jagti, NH-44, Nagrota Bypass, Jammu J&K, 181221, India.
The development of Michael addition reactions to conjugated cyclopropenes is a challenge in organic synthesis due to the fleeting and reactive nature of such strained Michael acceptor systems. Herein, the development of a photochemical approach towards such conjugated cyclopropenes is reported that serves as a strategic entry point to densely functionalized cyclopropanes in a diastereoselective fashion. The process involves the light-mediated generation of transient cyclopropenyl α,β-unsaturated esters from vinyl diazo esters, followed by an organic base catalyzed nucleophilic addition of N-heterocycles to directly access β-N-heterocyclic cyclopropanoic esters.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!