A strategy for site-selectively generating reactive N-acyliminium ion intermediates on a microelectrode array has been developed. The route capitalizes on the use of an electroauxiliary for building a methoxylated amino acid substrate, and then the electrochemical generation and solution phase confinement of acid in order to form the N-acyliminium ion. Keys to this strategy were the stability of an N-alpha-methoxyalkyl amide to basic reaction conditions and the generality of the electrogenerated acid conditions for conducting microelectrode array reactions in a site-selective fashion.
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http://dx.doi.org/10.1021/ol8007827 | DOI Listing |
Org Lett
November 2023
Molecular Synthesis Center & Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.
A highly efficient enantioselective enamine-catalyzed asymmetric conjugate addition has been developed to directly convert unfunctionalized cyclic α-hydroxyamides into chiral cyclic α-hydroxyamides by reacting with vinyl sulfones, which could be used as versatile azacyclic synthons in the following sequences: (1) as the precursors of cyclic -acyliminium ions to prepare natural productlike chiral azapolycyclic compounds under acidic conditions and (2) to construct chiral cyclic imides bearing unilateral substituents via oxidation reaction-induced formal desymmetrization.
View Article and Find Full Text PDFOrg Biomol Chem
November 2023
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
An efficient methodology for the synthesis of dihydro[1,2,3]triazolo-pyrimidoisoindolones and dihydro[1,2,3]triazolo-diazepinoisoindolones has been developed using the Huisgen reaction from sodium azide and alkyne substituted amido alcohols in moderate to good yields. The reaction involves the generation of the -acyliminium ion intermediate, which undergoes a nucleophilic attack by the azide ion, followed by a [3 + 2]-intramolecular azide-alkyne cycloaddition reaction. Importantly, the reaction proceeds without the involvement of any transition metal catalyst.
View Article and Find Full Text PDFMolecules
September 2023
Laboratory of Bioorganic Chemistry, Department of Physics, Università degli Studi di Trento, Via Sommarive 14, 38123 Trento, Italy.
Agelastatin A is a marine alkaloid with potent biological activity. To date, at least 17 different strategies have achieved its total synthesis, along with many analogues. The present study focuses on the acidity stability of some -methyl derivatives of agelastatin A.
View Article and Find Full Text PDFCarbohydr Res
June 2023
Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500 007, India. Electronic address:
A novel three-component strategy has been developed for the synthesis of iminosugars in good to excellent yields. This is the first report on the Mannich type addition of cyclic 1,3-diketones to aza-acetal derived from hydroxy-γ-lactone and arylamine to produce a novel series of aza-sugars with high selectivity.
View Article and Find Full Text PDFChem Asian J
June 2023
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Herein, we disclose a selective, versatile, accessible, cost-effective and highly efficient cation-exchange industrial grade INDION 130 resin as a reusable catalyst for the synthesis of 3-substituted isoindolinones from various γ-hydroxy lactams and a variety of C, N, O, and S nucleophiles involving N-acyliminium ion intermediates under mild reaction conditions. Mechanistic studies suggested the generation of a different kind of kinetically and thermodynamically controlled intermediates/eliminated products, which further converted to their corresponding products depending upon the nucleophile, reaction parameter and nitrogen substitution (benzyl vs. aryl) of the substrate (succinamidals vs.
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