Approaches to the synthesis of isocoumarins and 3,4-dihydroisocoumarins containing natural or synthetic amino-acid fragments are reviewed. Most attention is paid to the two most numerous groups of natural 3,4-dihydroisocoumarins, i.e., ochratoxins and amicoumacins.

ОПОВІДІ НАЦІОНАЛЬНОЇ АКАДЕМІЇ НАУК УКРАЇНИ ХІМІЯІзоксазоли -п'ятичленні гетероароматичні сполуки -мають широкий спектр корисних властивостей та майже невичерпні можливості практичного застосування [1].Ізоксазольний цикл як структурний фрагмент посідає 33-тє місце з 351 циклічної системи, представленої серед лікарських засобів [2].Так, діапазон біологічної активності фармацевтичних препаратів, які містять ізоксазольний цикл, досить різноманітний і включає протизапальну

The efficient synthesis of enaminoketones of 2'-carboxamidodeoxybenzoins and subsequent transformation into 1-oxo-3-aryl-1H-isochromene-4-carbaldehydes via an intermolecular cyclization under weakly acidic conditions has been demonstrated. Mild reaction conditions, a simple work-up procedure, short reaction times and high yields are the advantages of the presented method. (C) 2016 Elsevier Ltd. All rights reserved.

New amino-acid derivatives of 3-aryl-3,4-dihydroisocoumarins were prepared via acylation of the amine of natural amino acids by phenoxyacetic acids containing 3,4-dihydroisocoumarin substituents on the benzene ring.

An efficient approach based on pyrone ring opening in 3-arylisocoumarins in the presence of cyclic secondary amines was developed in order to prepare amides of deoxybenzoin-2'-carboxylic acids, diverse functionalized structures useful for the synthesis of polyfunctional compounds.

New amino-acid derivatives of 3-arylisocoumarins were prepared via acylation of the amine groups of natural amino acids by phenoxyacetic acids containing an isocoumarin substituent on the benzene ring.

Spectral and luminescent properties of substituted 7-hydroxycoumarins in solvents of various polarities are investigated and their luminescence spectra at temperature of liquid nitrogen are obtained. Sensor possibilities for ammonia vapor of coumarins in methylcellulose films are investigated.

A preparative method was developed for the synthesis of 3-(2-bromoacetyl)-1H-isochromen-1-one. Its heterocyclization to 3-(2-R-thiazol-4-yl)-, (3-quinoxalin-2-yl)-, and 3-(imidazo[1,2-a]pyridin-2-yl)-1H-isochromen-1-ones was studied.

Reduction of 3-(carboxyaryl)isocoumarins with sodium borohydride proceeds with formation of corresponding 3-carboxyaryl-3,4-dihydroisocoumarins or isomeric dihydrophthalides, 3-(2-carb-oxybenzyl)-2-benzofuran-1(3H)-ones. Derivatives at the carboxyl group of 3-carboxyaryl-3,4-dihydro-isocoumarins and 3-(2-carboxybenzyl)-2-benzofuran-1(3H)-ones have been obtained.

The interactions between coumarins and the surface of fumed SiO(2), CeO(2)/SiO(2), TiO(2)/SiO(2) and Al(2)O(3)/SiO(2) were assessed by means of temperature-programmed desorption mass spectrometry. The different stages of the thermolysis of coumarin were identified and an analysis of the underlying reactions was performed. The kinetic parameters of the involved reactions were thus obtained. The decomposition of thiazolyl-substituted coumarins was found to proceed through a 'thiazole-thiazine' ring expansion in the adsorbed state. A linear correlation between the sigma constants (Sigma sigma) of the coumarin substituents and the activation energy of CO(2) formation was obtained.

This paper describes the results of experimental studies to develop an electron beam technology for remelting raw silicon and further refining it in a vacuum.

The spectral-luminescent and lasing properties of the 3-substituted-7-hydroxycuomarins derivatives are studied experimentally and using quantum-chemical calculations using INDO method with spectroscopic parameterithation. The photophysical processes in these compounds were analyzed.

We have studied the characteristic features of the spectral fluorescence properties of natural compounds (umbelliferone and herniarin) in aprotic and proton-donor solvents of different polarities. Based on quantum chemical analysis by the AM1 semiempirical method of the changes in the electronic charge and bond orders in the ground state and the first excited state, we have interpreted the anomalously high Stokes shifts and mirror symmetry of the absorption and fluorescence bands of these compounds in aprotic solvents. We have established that the fluorescence spectra of umbelliferone in water, ethanol, alkaline and acidic solutions differ considerably from the analogous spectra of herniarin. This is connected with detachment and transfer of a proton in the neutral form of umbelliferone upon photoexcitation, with possible formation (depending on the pH of the medium) of an anion, cation, or tautomer. Good agreement was achieved between the calculated and experimental values of the maxima for the electronic bands of these forms.

The spectral, luminescent, and lasing properties of four derivatives of 7-hydroxycoumarin: 7-hydroxy-3-(4-methylthiazolyl)-coumarin (CI), 3-(4-methylthiazolyl)-2-oxocoumarin-furan-2-carboxylate (CII), 3-(4-(benzo[1,3]dioxolyl)-thiazolyl)-2-oxocoumarin-furan-2-carboxylate (CIII), and 3-(4-(benzo[1,3]dioxolyl)-thiazolyl)-2-hydroxycoumarin (CIV), as well as of their protolytic forms, are studied experimentally and theoretically by the INDO/S method. The luminescence quantum yield of the CIII and CIV compounds, having bulky substituents at position 3, is shown to strongly depend on the polarity of a solvent. It is suggested that, in polar solvents, these substituents are displaced out of the plane of the skeleton of the electronically excited molecule. The quantum-chemical calculations of such structures confirmed their weak fluorescence ability due to intense intersystem crossing. The lasing ability of the protolytic forms of the compounds considered is studied. The reason for the absence of lasing for the neutral compounds is discussed.

The luminescence spectral properties of 3-pyridyl-7-hydroxy-2-iminocoumarin and 3-(2-methylthiazole)-7-hydroxy-2-iminocoumarin were studied in ethanol solutions at different values of pH and also in other solvents differing in polarity. In their ethanol solutions, the compounds can exist as neutral molecules, anions, cations, and zwitterions. The spectral properties and geometry were studied for all possible forms of these compounds by the INDO/S quantum-chemical method.