Simple and mild methods for the synthesis of allenes, employing indium- and zinc-mediated dehalogenation reactions of vicinal dihalides in an aqueous solvent, are described. By using these procedures, various allenylmethyl aryl ethers and monosubstituted allenes have been prepared in good to excellent yields.
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Chem Commun (Camb)
January 2025
Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, MP, India.
We report herein a palladium-catalyzed distal alkylation of silyldienol and silyltrienol ethers of enones through coupling with activated halides to achieve new - and -alkylated motifs. Additionally, by employing propargyl bromides, synthetically useful linear allenes along with functionalized enones have been synthesized. Low-catalyst loading, and late-stage transformations of pharmaceutically relevant molecules further showcase the importance of the present protocol.
View Article and Find Full Text PDFAcc Chem Res
October 2024
School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore.
ConspectusSynergy between the teaching and research activities of a University should be a source of new ideas, each informing the other. A classroom discussion gave rise to our concept of using hydroxylamines as a form of "tethered nitrogen" for alkaloid synthesis. The "tether" temporarily connects a nucleophilic nitrogen atom to the substrate, rendering an intermolecular reaction intramolecular, thus providing stereo- and regiochemical control for C-N bond formation.
View Article and Find Full Text PDFMolecules
August 2024
Institute of Biochemistry, Bioinorganic Chemistry, University of Greifswald, Felix-Hausdorff-Str. 4, 17489 Greifswald, Germany.
1,2,3,4,5-pentathiepines (PTEs) are naturally occurring polysulfides of increasing scientific interest based on their identified pharmacological activities. Artificial PTEs with -heterocyclic backbones are efficiently synthesized via mediation by a molybdenum-oxo-bistetrasulfido complex. A common feature of all precursor alkynes successfully used to date in this reaction is the presence of a -CH(OEt) group since the previously postulated mechanism requires the presence of one OEt as the leaving group, and the second must become a transient ethoxonium moiety.
View Article and Find Full Text PDFOrg Lett
September 2024
Department of Chemistry and Biochemistry, Baylor University, One Bear Place 97348, Waco, Texas 76798, United States.
Herein we describe a total synthesis of the heterodimeric securinega alkaloid (-)-flueggeacosine C (). The convergent synthetic strategy is based on a Liebeskind-Srogl cross-coupling reaction that combines a benzoquinolizidine fragment with a securinine-type alkaloid. An acyloxy nitroso ring-expansion was employed as the key step in accessing benzoquinolizidine , and a novel intramolecular Diels-Alder reaction of an allenic acid-containing pyridone expeditiously delivers the skeleton of the securinine-type fragment ().
View Article and Find Full Text PDFOrg Lett
September 2024
Department of Chemistry, University of Illinois Chicago, 845 W. Taylor St., Chicago, Illinois 60607, United States.
1,3-Diynyl propiolates undergo the Alder-ene reaction to generate enyne-allenes, which participate in the Diels-Alder reaction to provide products of a formal [2 + 2 + 2] cycloaromatization of three alkynes. Without an external alkyne, enyne-allene reacts with one of the alkyne moieties of 1,3-diynyl propiolate, whereas external alkynes can be used to trap enyne-allene to provide various arene products. The substituents on the dienophilic alkynes have a profound impact on their reactivity.
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