N-Substituted 7-aminocoumarins can be synthesized from readily available 7-hydroxycoumarins via alkylation with α-bromoacetamides and subsequent tandem O → N Smiles rearrangement-amide hydrolysis. The key rearrangement sequence proceeds under mild conditions to provide convenient access to various -alkyl and -aryl products in moderate to high yields. The process is operationally simple, inexpensive, transition-metal-free, and can be telescoped into a one-pot process.
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Synthesis of 7-Aminocoumarins from 7-Hydroxycoumarins via Amide Smiles Rearrangement.
ACS Omega
October 2022
Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, United States.
N-Substituted 7-aminocoumarins can be synthesized from readily available 7-hydroxycoumarins via alkylation with α-bromoacetamides and subsequent tandem O → N Smiles rearrangement-amide hydrolysis. The key rearrangement sequence proceeds under mild conditions to provide convenient access to various -alkyl and -aryl products in moderate to high yields. The process is operationally simple, inexpensive, transition-metal-free, and can be telescoped into a one-pot process.
View Article and Find Full Text PDFChanges in energy of three types of hydrogen bonds upon excitation of aminocoumarins determined from absorption solvatochromic experiments.
Phys Chem Chem Phys
June 2011
Photochemistry and Spectroscopy Laboratory, Faculty of Chemistry, Adam Mickiewicz University, Poznań, Poland.
Absorption spectra of 6-aminocoumarin (6AC) and 7-aminocoumarins (C120 and C151) were studied in polyfluorinated alcohols: (1,1,1,3,3,3-hexafluoroisopropanol (HFIP), 2,2,2-trifluoroethanol (TFE)), in water and in methanol, and compared to those taken in 1-chloro-n-alkanes. According to our results, the observed unusual blue-shift of a long-wavelength band in absorption spectra in strong protic solvents is direct evidence of significant weakening of a NH-O hydrogen bond. The results obtained for the aminocoumarins in HFIP, which in contrast to aliphatic alcohols does not form hydrogen bonds of the acceptor type, prove that the decrease in the energy of the NH-O hydrogen bond upon excitation to the lowest S(1)-LE state is significantly greater than the increase in the energy of hydrogen bonds made by the oxygen atom of carbonyl group OH-O.
View Article and Find Full Text PDFIntramolecular fluorescence quenching of crowned 7-aminocoumarins as potential fluorescent chemosensors.
J Fluoresc
March 2004
Chemistry Department, Lomonosov Moscow State University, 119899 Moscow, Vorob'evy gory, Russia.
The effects of the nature of solvent, temperature and complex formation with alkali and alkaline-earth metal cations, as well as protonation, on the efficiency and the kinetics of fluorescence of 3-azacrowned 7-diethylaminocoumarins have been studied. For the crown-ethers under investigation, the ratio of a dipole moment to the radius of Onsager cavity delta micro/rho is a constant value, and a macrocycle does not affect delta micro, and rho. The fluorescence of coumarin 1 in acetonitrile is quenched by an electron donor, triethylamine, with the Stern-Volmer constant being equal to (0.
View Article and Find Full Text PDF7-Aminocoumarins are substrates of cytochrome P450-isozymes.
Arch Pharm (Weinheim)
April 1998
University of Marburg, School of Medicine, Germany.
N-Alkyl-7-aminocoumarins are dealkylated by murine cytochrome P450. There are differences between the N-dealkylation of secondary and tertiary amines. 7-Ethylamino-4-methylcoumarin is deethylated by isozymes induced by 3-methylcholanthrene, in contrast to 7-diethylamino-4-methylcoumarin and 7-diethyl-amino-4-trifluoromethylcoumarin, which are deethylated mostly by isozymes induced by phenobarbital.
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