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The LANCA three-component reaction of lithiated alkoxyallenes , nitriles and carboxylic acids leads to β-ketoenamides in good to excellent yields. The scope of this reaction is very broad and almost all types of nitriles and carboxylic acids have successfully been used. The alkoxy group introduced via the allene component is also variable and hence the subsequent transformation of this substituent into a hydroxy group can be performed under different conditions. Enantiopure nitriles or carboxylic acids can also be employed leading to chiral with high enantiopurity and dinitriles or dicarboxylic acids also lead to the expected bis-β-ketoenamides. β-Ketoenamides incorporate a unique combination of functional groups and hence a manifold of subsequent reactions to highly substituted heterocyclic compounds is possible. An intramolecular aldol-type condensation reaction efficiently furnishes pyridin-4-ols that can be further modified by palladium-catalyzed reactions, e.g., to specifically substituted furopyridine derivatives. Condensations of β-ketoenamides with ammonium salts or with hydroxylamine hydrochloride afford pyrimidines or pyrimidine -oxides with a highly flexible substitution pattern in good yields. The functional groups of these heterocycles also allow a variety of subsequent reactions to various pyrimidine derivatives. On the other hand, acid-labile alkoxy substituents such as a 2-(trimethylsilyl)ethoxy group are required for the conversion of β-ketoenamides into 5-acetyl-substituted oxazoles , again compounds with high potential for subsequent functional group transformations. For acid labile β-ketoenamides bearing bulky substituents the acid treatment leads to acylamido-substituted 1,2-diketones that could be converted into quinoxalines . All classes of heterocycles accessed through the key β-ketoenamides show a unique substitution pattern - not easily accomplishable by alternative methods - and therefore many subsequent reactions are possible.
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http://dx.doi.org/10.3762/bjoc.15.61 | DOI Listing |
Acta Crystallogr E Crystallogr Commun
October 2024
Institut für Organische Chemie Technische Universität Bergakademie, Freiberg, Leipziger Str 29 09599 Freiberg/Sachsen Germany.
Crystal growth of 2-(3,4,5-triphen-ylphen-yl)acetic acid () from aceto-nitrile yields a monosolvate, CHO·CHCN, of the space group 1. In the crystal, the title mol-ecule adopts a conformation in which the three phenyl rings are arranged in a paddlewheel-like fashion around the central arene ring and the carboxyl residue is oriented nearly perpendicular to the plane of this benzene ring. Inversion-symmetric dimers of O-H⋯O-bonded mol-ecules of represent the basic supra-molecular entities of the crystal structure.
View Article and Find Full Text PDFInt J Mol Sci
November 2024
College of Life Sciences, Northeast Agricultural University, Changjiang Road, Xiangfang District, Harbin 150038, China.
Nitrilases, found to have a common presence in the plant kingdom, are capable of converting nitriles into their corresponding carboxylic acids through hydrolysis. In Arabidopsis, the nitrilases NIT1, NIT2, and NIT3 catalyze the formation of indole-3-acetonitrile (IAN) into indole-3-acetic acid (IAA). Notably, IAN can originate from the breakdown products of indole glucosinolates.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
November 2024
Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States.
Peptide conjugates furnished with a 2,5-diaryltetrazolecarbonyl tag at the C-terminal lysine, which we call peptide--K, were found to undergo efficient cross-linking of Asp, Glu, Asn, and Gln residues to transient nitrile-imine intermediates produced by photodissociation and collision-induced dissociation (CID) of the tetrazole ring in gas-phase ions. UV photodissociation (UVPD) at 213 nm achieved cross-linking conversion yields of 37 and 61% for DAAAK--K and EAAAK--K, respectively. The yields for NAAAK--K and QAAAK--K were 29 and 57%, respectively.
View Article and Find Full Text PDFJ Colloid Interface Sci
February 2025
School of Chemical Engineering, Northwest University, Xi'an 710069, China. Electronic address:
High performance film capacitor has attracted widespread attention due to their increasing applications in electronic devices. However, the insufficient dielectric properties of dielectrics in capacitors severely restrict their practical application. In this work, the dielectric performances of polyarylene ether nitrile (PEN) are effectively enhanced by the synthesizing and employing of carboxylated PEN (CPEN) modified one-dimensional (1D) strontium barium titanate nanorod (BSTNR) (CPEN@BSTNR), as well as applying of hot stretching technique.
View Article and Find Full Text PDFAcc Chem Res
December 2024
Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
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