In a previous work (L. R. Domingo, M. J. Aurell, P. Perez and R. Contreras, Tetrahedron 2002, 58, 4417) we proposed that the difference in global electrophilicity index be taken as a measure of the polarity at the transition state in intermolecular Diels-Alder reactions. We herein extend this model to deal with intramolecular Diels-Alder (IMDA) processes. The transferability of the empirical reactivity rules established for the intermolecular DA reactions to the IMDA reactions is discussed. The analysis based on group electrophilicity and nucleophilicity in general fails because having two different reactivity patterns within the same molecule hampers a clean classification of electrophilicity and nucleophilicity of the interacting fragments. We introduce dual philicity indexes E1 and E2 that solve this problem by separating a series of 30 IMDA reactions into two families, namely the diene to dienophile electron flow (DDpF) and the dienophile to diene electron flow (DpDF) processes. The new indexes correctly describe the charge transfer at the transition state and the reaction mechanism expected for the title reactions.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/c004628k | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Efficient synthesis of fluorinated triphenylenes with enhanced arene-perfluoroarene interactions in columnar mesophases.
Beilstein J Org Chem
December 2024
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg (UMR 7504), F-67034 Strasbourg, France.
The high potential of non-covalent arene-fluoroarene intermolecular interactions in the design of liquid crystals lies in their ability to strongly promote self-assembly, improve the order and stability of the supramolecular mesophases, and enable tuneability of the optical and electronic properties, which can potentially be exploited for advanced applications in display technologies, photonic devices, sensors, and organic electronics. We recently successfully reported the straightforward synthesis of several mesogens containing four lateral aliphatic chains and derived from the classical triphenylene core self-assembling in columnar mesophases based on this paradigm. These mesogenic compounds were simply obtained in good yields by the nucleophilic substitution (SFAr) of various types of commercially available fluoroarenes with the electrophilic organolithium derivatives 2,2'-dilithio-4,4',5,5'-tetraalkoxy-1,1'-biphenyl (2Li- ).
View Article and Find Full Text PDFd-Galactose-Esterification of a Fungal Polyketide Catalyzed by a Carnitine Acyltransferase Domain.
Chembiochem
December 2024
University of California Los Angeles, Dept. of Chemical And Biomolecular Engineering, 5531 Boelter Hall, 420 Westwood Plaza, 90095, Los Angeles, UNITED STATES OF AMERICA.
While sugar-containing natural products are commonly biosynthesized via glycosyltranferases using sugar-UDP as the electrophile, nature has evolved alternative strategies of glyco-modification to expand the diversity of natural products. Hydroxyl groups on sugars can serve as nucleophiles in the release of polyketide products from polyketide synthases. Herein, we demonstrate a highly reducing polyketide synthase (HRPKS) from the biocontrol fungus Trichoderma afroharzianum T22, which is terminated with a carnitine acyltransferase (cAT) domain, catalyzes the biosynthesis of a d-galactose esterified polyketide named as trichogalactin.
View Article and Find Full Text PDFThree Dihydroquinolin-4-one Derivatives as Potential Biodiesel Additives: From the Molecular Structure to Machine Learning Approach.
ACS Omega
December 2024
Grupo de Química Teórica e Estrutural de Anápolis, Universidade Estadual de Goiás, 75132-903 Anápolis, GO, Brasil.
Biodiesel offers an alternative to fossil fuels, primarily because it is derived from renewable sources, with the potential to mitigate issues such as pollutant and greenhouse gas emissions, resource scarcity, and the market instability of petroleum derivatives. However, lower durability and stability pose challenges. To address this, researchers worldwide are exploring technologies that employ specific molecules to slow down biodiesel's oxidation process, thereby preserving its key physicochemical properties.
View Article and Find Full Text PDFCySP3-96 enables scalable, streamlined, and low-cost sample preparation for cysteine chemoproteomic applications.
Mol Cell Proteomics
December 2024
Biological Chemistry Department, David Geffen School of Medicine, UCLA, Los Angeles, CA, 90095, USA; Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, 90095, USA; Molecular Biology Institute, UCLA, Los Angeles, CA, 90095, USA; DOE Institute for Genomics and Proteomics, UCLA, Los Angeles, CA, 90095, USA; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, UCLA, Los Angeles, CA, 90095, USA. Electronic address:
Cysteine chemoproteomic screening platforms are widely utilized for chemical probe and drug discovery campaigns. Chemoproteomic compound screens, which use a mass spectrometry-based proteomic readout, can interrogate the structure activity relationship (SAR) for thousands of proteins in parallel across the proteome. The versatility of chemoproteomic screens has been demonstrated across electrophilic, nucleophilic, and reversible classes of molecules.
View Article and Find Full Text PDFADP-ribosyltransferase-based biocatalysis of non-hydrolyzable NAD+ analogs.
J Biol Chem
December 2024
Institute of Biomedicine, University of Turku, Turku, Finland.
Enzyme promiscuity is the ability of an enzyme to catalyze an unexpected side reaction in addition to its main reaction. Here, we describe a biocatalytic process to produce non-hydrolyzable NAD+ analogs based on the ADP-ribosyltransferase (ART) activity of pertussis toxin PtxS1 subunit. First, in identical manner to normal catalysis, PtxS1 activates NAD+ to form the reactive oxocarbenium cation.
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!