Please login first

List of accepted submissions

Show results per page
Find papers
  • Open access
  • 74 Reads
Synthesis of furo[3,2-b]pyrrole-5-carboxhydrazides and Their Cu, Ni and Co Complexes
N\'-[(4-oxochromen-3-yl)methylidene]-4-R-furo[3,2-b]pyrrole-5-carboxhydrazides 3 were prepared by treatment of substituted carboxhydrazides 1 with 4-oxo-4H-chromen-3-carboxaldehyde 2 in ethanol in the presence of p-TsOH. Compounds 3 were subsequently used as ligands in complexation reactions with solutions of metal (M2+) chlorides or nitrates: [Ni(NO3)2.6H2O, Co(NO3)2.6H2O, CoCl2.6H2O, CuCl2.2H2O] to give complexes 4.
  • Open access
  • 65 Reads
Alternative synthetic approaches to biologically active indeno[1,2-c]isoquinoline-5,11-diones
, , , ,
Indenoisoquinolinediones, as exemplified by lead compounds indotecan and indimitecan, are a class of non-camptothecin topoisomerase I poisons that display marked cytotoxic properties and for some of them antitumor activities in xenograft models. We have developed two alternative and dramatically different synthetic approaches to a variety of highly fused and diversely substituted models that differ from the elaboration of key precursors, i.e. arylated 2,3-dihydroisoquinolones. The first one is based upon a Suzuki-Miyaura cross-coupling reaction involving enol phosphates combined with a ring-closing metathesis (RCM) reaction to ensure the creation of the six-membered lactam unit. The second approach hinges upon the photoinduced electrocyclization of the 6π electron aromatic enamides. The presence of phenolic methoxy groups precluded an additional mandatory and problematic oxidation step to generate the unsaturated lactam ring. Intramolecular carbocationic annulation reaction and ultimate oxidation of the latent hydroxyl functionality completed the synthesis of the targeted title compounds.
  • Open access
  • 120 Reads
Convenient synthesis of functionalized α-methylenebutano-4-lactams or lactones
, , ,
α-Alkylidene-γ-lactams and lactones are the active constituents of many natural and synthetic compounds exhibiting pronounced biological properties. They are able to act as Michael acceptors in the reaction with thiol groups of bionucleophiles or can readily form [2 + 2] cycloadducts with DNA bases. We have developed concise synthetic approaches towards exemplary representatives of α-methylene models that hinges upon the preliminary assembly of the lactam and lactone template. Subsequent installation of the methylidene by a metallation/alkylation/elimination sequence completed the elaboration of the racemic title compounds. The presence of a quaternary carbon center bearing the carboxylate function precluded the undesirable isomerization leading to the corresponding endocyclic unsaturated analogues.
  • Open access
  • 109 Reads
Silylation of cellobiose as a model reaction for the synthesis of silylated cellulose. A DFT and PM3 approach.
, , ,
The object of the present study is the isodesmic reaction of cellobiose (the repeating unit in cellulose) with different kinds of silanes, R-SiH3, to form silylated cellobiose (Cello-SiH3) and the corresponding alcohols (R-OH). The size and the chemical reactivity of the substituent R is varied as well as the position where O-silylation at the cellobiose takes place. In contrast to experimental observations where the O6 position is favored for silylation, for the computed reactions, energy differences are smaller than 3 kcal/mol for the different positions at the B3LYP/6-311G* as well as at the B3LYP/6-311+G* level of theory. Depending on the silane, reaction energies in a range from -17 kcal/mol (R=NHSiH3) and +18 kcal/mol (R=F) have been calculated. In addition, semi-empirical calculations on the PM3 level of theory have been performed. These results are set into contrast with the results derived from DFT calculations to assess whether semi-empirical methods may be useful for the description of larger systems containing silylated cellobiose units. Acknowledgements: The research leading to these results has received funding from the European Community\'s Seventh Framework Programme [FP7/2007–2013] under grant agreement no. 214015 (S.S. and H.M.A.E.) and no. 214653.
  • Open access
  • 75 Reads
Synthesis and properties of cyclodextrin-malic acid copolymers
Cyclodextrins polymers are known as an interesting low molecular carriers in pharmacy, food technology, medicine etc. There are different routes to design such kind of macromolecules however most of them base on synthetic compound. In the presented work a series of cyclodextrin polyesters with malic acid were obtained using dry method. Sodium hydrogen phosphate was used as a catalyst. As a result two different fractions were obtained i.e. water soluble and insoluble ones. Both of them were characterized by means of carboxylic acid (HPLC) and carbohydrates profile (anthron method) . Several malic acid derivatives were detected especially fumaric and malonic acids. In obtained sample the complexation ability was checked using standard methyl orange method. The insoluble fraction was hydrolyzed using sodium carbonate solution and the carboxylic acids and cyclodextrin presence were investigated as well. According to obtained results we can state the novel cyclodextrin macromolecules were design using simple and easy protocol. The obtained product is fully biodegradable and completely nontoxic what guides to many possible application in both food and non-food application.
  • Open access
  • 88 Reads
Green approach to the design of functionalized medicinally privileged 4-aryl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile scaffold !
, ,
The main objective of the project was to find conditions of the synthesis of pyrano[2,3-c]pyrazoles in accordance with the principles of "green" chemistry. Pyrano[2,3-c]pyrazoles possess a broad spectrum of biological activity. For example, they can be used as anticancer agents and enzyme inhibitors. Known methods for the synthesis of such compounds involve using large volumes of toxic solvents and are complicated in usage. In the course of the our work the reactions between malononitrile, 3-methyl-2-pyrazoline-5-one and benzaldehyde under solvent-free conditions and in small quantity of water in the presence of various amounts of non-toxic bases (potassium fluoride, sodium acetate, and sodium hydroxide) were studied. As a result, optimal conditions for the synthesis of 6-amino-3-methyl-4-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (one of the simplest pyrano[2,3-c]pyrazoles) have been found. These conditions were tested on synthesis of difficult functionally substituted pyrano[2,3-c]pyrazoles. Thus, it was found that in optimal conditions the reaction between malononitrile, 3-methyl-2-pyrazoline-5-one and aromatic aldehydes in small quantity of water and in the presence of 5 mol.% of sodium hydroxide leads to pyrano[2,3-c]pyrazoles selectively in high yield (more than 93%). Carrying out the reaction in water and using sodium hydroxide as the base allows to reduce the cost of the process and significantly improve its environmental friendliness. Using small amounts of water allows to use the working capacity of a chemical reactor more efficiently and to avoid significant losses at the isolation stage. Thus, the proposed process is more efficient and environmentally friendly compared to those known today.
  • Open access
  • 86 Reads
Pentafluorophenylammonium triflate (PFPAT): an efficient, practical, and cost-effective organocatalyst for bigginelli reaction
A simple, inexpensive, environmentally friendly and efficient route for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives via the one-pot three-component Biginelli reaction using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures.
  • Open access
  • 57 Reads
Synthesis of 2,1-benzisoxazol-3(1H)-one by intramolecular photochemical cyclization of 2-azidobenzoic acid.
, ,
Peculiarities of 2,1-benzisoxazol-3(1H)-one synthesis by means of the photochemical cycle forming reaction of 2-azidobezoic acid in ethanol. Based upon HPLC kinetical data we have observed the 2,1-benzisoxazol-3(1H)-one yield decrease in the course of decreasing of the starting azide concentration. It was stated that the 2,1-benzisoxazol-3(1H)-one formation effectiveness depended on the actinic light wavelength. Changing the light wavelength from 365 to 253.7 nm we observed an increase of the cycle formation yield. The decrease of the 2,1-benzisoxazol-3(1H)-one yield in the course of irradiating at 365 nm was explained by the secondary photolysis.
  • Open access
  • 71 Reads
Preparation and Herbicidal Properties of Ring-Substituted 4-Chloro-2-styrylquinazolines
, , , , , ,
In this study, a series of new seven ring-substituted 4-chloro-2-styrylquinazoline derivatives were prepared. The procedures for synthesis of the compounds are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed, as well as their structure-activity relationships (SAR).
  • Open access
  • 78 Reads
Preparation and Herbicidal Properties of Substituted Quinoline-2-carboxanilides
In this study a series of twenty-five substituted quinoline-2-carboxanilides were prepared. The procedures for synthesis of the compounds are presented. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. For all the compounds the structure-activity relationships (SAR) are discussed.