A single alkynyl vinylogous carbonate was elaborated to tetrasubstituted furan or dihydrofuran via a cascade inter-intramolecular radical reaction by changing the radical being added. The strategy could be used in the synthesis of polycyclic heterocycles as well as bis-furan exhibiting atropisomerism. Installation of a new furan motif on the existing one was feasible by iteration. Stannyl dihydrofuran derivative was used in Stille coupling, whereas intramolecular Friedel-Crafts acylation on the furan gave furanonaphthol.
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http://dx.doi.org/10.1021/acs.orglett.8b03668 | DOI Listing |
Acc Chem Res
January 2025
Department of Chemistry and Chemistry Institution for Functional Materials, Pusan National University, Busan 46241, Republic of Korea.
ConspectusControlling selectivity through manipulation of reaction intermediates remains one of the most enduring challenges in organic chemistry, providing novel solutions for selective C-C π-bond functionalization. This approach, guided by activation principles, provides an effective method for selective functional group installation, enabling direct synthesis of organic molecules that are inaccessible through conventional pathways. In particular, the selective functionalization of N-conjugated allenes and alkynes has emerged as a promising research focus, driven by advances in controlling reactive intermediates and activation strategies.
View Article and Find Full Text PDFChemistry
November 2024
Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, Illinois, 60607, USA.
We describe novel amine-mediated transformation of alkynyl ketones and amides to generate 2-methylene-2H-pyrans, substituted 3-hydroxy-9H-fluoren-9-ones, and amine-incorporated arenes. These cascade processes are initiated by conjugate addition of secondary amine followed by hydrolysis of the enamine/vinylogous amide intermediates. The product distribution is highly sensitive to the steric and electronic effects of the substituents on both the alkyne moieties, the tether structure connecting them, and the nature of the amine.
View Article and Find Full Text PDFOrg Lett
February 2024
Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, China.
We report a Cu(I)-Ph-BPE-catalyzed asymmetric vinylogous Mannich reaction of β,γ-alkynyl-α-ketimino esters with β,γ-unsaturated -acylpyrazoles. In this process, the Cu(I)-Ph-BPE catalyst activates the β,γ-alkynyl-α-ketimino ester through N,O-coordination, enabling the subsequent nucleophilic addition of a dienolate generated from the β,γ-unsaturated -acylpyrazole via α-position deprotonation with a catalytic amount of tertiary amine. The reactions gave useful products with very high enantioselectivities.
View Article and Find Full Text PDFJ Am Chem Soc
August 2022
CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide & Chemical Biology Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P.R. China.
Distinct regio- and enantioselectivity control in copper-catalyzed vinylogous and bisvinylogous propargylic substitution has been accomplished by using a novel chiral ,, ligand. The developed method provides an efficient and selective approach to an array of highly enantioenriched alkynyl unsaturated carbonyl compounds. Salient features include excellent functional group tolerance and broad substrate scope.
View Article and Find Full Text PDFChem Commun (Camb)
August 2022
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India.
TMSOTf-mediated reaction of alkynyl vinylogous carbonates serendipitously gave 1,4-oxazepine and dihydropyran dienes transposition of an ethyl acrylate moiety involving intramolecular cascade Prins-type cyclization/retro-oxa-Michael reaction/cycloisomerisation. The developed atom-economical protocol selectively provides an double bond geometry. Dihydropyran dienes could be reduced diastereoselectively using EtSiH/TMSOTf or could be transformed into polycyclic heterocycles by Heck reaction.
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