Inese Mieriņa

Synthetic approaches to 4-(het)aryl-3,4-dihydroquinolin-2(1H)-ones

This review summarizes strategies for the synthesis of 4-(het)aryl-3,4-dihydroquinolin-2(1H)-ones which are of interest due to their biological activity. It covers methods elaborated particularly for obtaining the title heterocycles, as well as procedures where these compounds are formed as side products. 4-Aryl-3,4-dihydroquinolin-2(1H)-one derivatives have been used for the synthesis of valuable molecules, e.g., anticancer drug tipifarnib.

Nitroolefins as starting materials for 5-membered N-heterocycles

Nitroolefins are widely used for the synthesis of valuable cyclic and acyclic compounds. Synthesis of polysubstituted pyrrolidines and 1 H -pyrroles, as well as the skeleton of spiroindolinopyrrolidin-2-one starting from the title compounds is well known. Herein the recent (2013–2015) examples leading to five-membered nitrogen heterocycles (with exception of the above-mentioned structures) are focused. How to Cite Mieriņa, I.; Jure, M. Chem. Heterocycl. Compd. 2016 , 52 , 10. [ Khim. Geterotsikl. Soedin. 2016 , 52 , 10.] For this article in the English edition see DOI 10.1007/s10593-016-1823-9

ALKYLIDENE AND ARYLIDENE MELDRUM'S ACIDS AS VERSATILE REAGENTS FOR THE SYNTHESIS OF HETEROCYCLES

Meldrums acid and its derivatives are excellent building blocks for the synthesis of acyclic, carbocyclic and heterocyclic compounds. Herein recent (mainly 2010–2015) trends on applications of arylidene/alkylidene Meldrums acids (R 1 , R 2 = H, Ar, Alk, –(CH 2 ) n –) in the synthesis of heterocycles and multicomponent reactions (MCR) involving in situ formation of arylidene/alkylidene Meldrums acids are focused. How to Cite Mieriņa, I.; Jure, M. Chem. Heterocycl. Compd. 2016 , 52 , 7. [ Khim. Geterotsikl. Soedin. 2016 , 52 , 7.] For this article in the English edition see DOI 10.1007/s10593-016-1822-x

Synthesis and Antiradical Properties of 4-Aryl-3,4-Dihydroquinolin-2-(1H)-Ones, Aza Analogs of Neoflavonoids

A convenient one-pot method is proposed for the synthesis of 4-aryl-3,4-dihydroquinolin-2(1H)-ones from the monoanilides of malonic acid and aromatic aldehydes. The antiradical activity of the synthesized 4-aryl-3,4-dihydroquinolin-2(1H)-ones was examined (tests on the inhibition of 2,2-di-phenyl-1-picrylhydrazyl and galvinoxyl). It was found that the highest antiradical activity is exhibited by derivatives of syringaldehyde; the activity of the other compounds is moderate or low, however in the 2,2-diphenyl-1-picrylhydrazyl inhibition test it is comparable with or higher than for the widely used antioxidant Ionol.

Synthesis and antioxidant activity of new analogs of Quin-C1

New derivatives of 4-oxo-1,2,3,4-tetrahydroquinazoline, analogs of Quin-C1, have been synthesized by the condensation of aroyl- and heteroaroylhydrazides of anthranilic acid with cinnamic, crotonic, and 4-hydroxy-3-methoxybenzoic aldehydes. The antioxidant activity of the obtained compounds has been determined.

Synthesis of novel lupane triterpenoid-indazolone hybrids with oxime ester linkage.

Graphical abstract Figure. No Caption available. HighlightsNovel lupane triterpenoid‐indazolone hybrids with oxime linkage are obtained.This is the first report on oxime esters derived from betulonic and betulinic acid at their C(28).X‐ray structure of the hybrid molecule is reported.Purification procedure for betulonic acid via its cyclohexylammonium salt is developed. Abstract An efficient protocol for the synthesis of novel lupane triterpenoid‐indazolone hybrids with oxime ester linkage has been developed from naturally accessible precursor betulin. For the first time a series of betulonic acid‐indazolone hybrids have been synthesized via an acylation of corresponding 6,7‐dihydro‐1H‐indazol‐4(5H)‐one oximes with betulonic acid chloride. Diastereoselective reduction of the obtained betulonic acid conjugates with NaBH4 resulted in a formation of betulinic acid‐indazolone hybrids in excellent yields. The configuration of the key compounds has been fully established by X‐ray and 2D NMR analysis.

Extracts of Peppermint, Chamomile and Lavender as Antioxidants

This paper is devoted to the studies of total polyphenol content and antiradical activity of peppermint, chamomile and lavender grown in local backyard gardens of Latvia. Different solvents (96, 70 and 40% ethanol) and extraction methods (maceration at room temperature at dark or under day-light irradiation, as well as reflux) were tested. All extracts were analyzed for total polyphenol content (Folin–Ciocalteu method), as well as for antiradical activity (DPPH and GO assays). It was found out that local peppermint and chamomile is as good source of polyphenols as those plants grown in southern countries; however, the total polyphenol content of lavender is lower than that mentioned in literature. The highest polyphenol content for all plant materials was achieved, when 70% ethanol was used for extraction. Peppermint extracts were found as most powerful free radical scavengers among all tested plant materials. 96% Ethanol extract of peppermint and chamomile demonstrated the highest antiradical activity, while 70% ethanol was the most suitable for preparation of lavender extract with optimal free radical scavenging activity.

Antioxidant Properties of Camelina sativa Oil and Press-Cakes

Abstract Camelina sativa is well known due to high content of polyunsaturated fatty acids in its oil. Till now this oil has been studied mainly for applications as raw material for synthesis of resins, biodiesel and hydrocarbon fuels. This study examines the oxidative stability of cold-pressed Camelina sativa (also known as camelina, false flax or gold-of-pleasure) oil and its extracts of spices. Despite the high content of polyunsaturated fatty acids, Camelina sativa oil appeared more rigid against oxidation than rapeseed or flax oil. Extracts of different spices were prepared by maceration in camelina oil at room temperature for 24 h. The stability of extracts was determined under accelerated oxidation conditions and monitored by peroxide values. Most of the tested additives (e.g., bay leaves, allspice, clove, barley sprouts, coriander, ginger) did not influence or even decreased oxidative stability of the oil. However, oil with thyme additive demonstrated remarkably higher stability then Camelina sativa oil alone. Press-cakes of camelina seeds were extracted with two polar solvents (ethanol or water) and their mixtures under variable conditions (room temperature or reflux). Prepared polar extracts of press-cakes were characterised by total polyphenol content (Folin–Ciocalteu method) and antiradical activity against 1,1-diphenyl-2-picryl hydrazyl and galvinoxyl.