- Substituted dienes prepared from betulinic acid – Synthesis, cytotoxicity, mechanism of action, and pharmacological parameters
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A set of new substituted dienes were synthesized from betulinic acid by its oxidation to 30-oxobetulinic acid followed by the Wittig reaction. Cytotoxicity of all compounds was tested in vitro in eight cancer cell lines and two noncancer fibroblasts. Almost all dienes were more cytotoxic than betulinic acid. Compounds 4.22, 4.30, 4.33, 4.39 had IC50 below 5 μmol/L; 4.22 and 4.39 were selected for studies of the mechanism of action. Cell cycle analysis revealed an increase in the number of apoptotic cells at 5 × IC50 concentration, where activation of irreversible changes leading to cell death can be expected. Both 4.22 and 4.39 led to the accumulation of cells in the G0/G1 phase with partial inhibition of DNA/RNA synthesis at 1 × IC50 and almost complete inhibition at 5 × IC50. Interestingly, compound 4.39 at 5 × IC50 caused the accumulation of cells in the S phase. Higher concentrations of tested drugs probably inhibit more off-targets than lower concentrations. Mechanisms disrupting cellular metabolism can induce the accumulation of cells in the S phase. Both compounds 4.22 and 4.39 trigger selective apoptosis in cancer cells via intrinsic pathway, which we have demonstrated by changes in the expression of the crucial apoptosis-related protein. Pharmacological parameters of derivative 4.22 were superior to 4.39, therefore 4.22 was the finally selected candidate for the development of anticancer drug.
- Frydrych, Ivo,Urban, Milan,?arek, Jan,Benická, Sandra,D?ubák, Petr,Gurská, Soňa,Hajdúch, Marián,Kotulová, Jana,Li?ková, Barbora,Olejníková, Denisa,Pokorny, Jan
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- Chromene- And quinoline-3-carbaldehydes: Useful intermediates in the synthesis of heterocyclic scaffolds
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Chromenes and quinolines are recognized as important scaffolds in medicinal chemistry. Herein, the efficient use of chromene- and quinoline-3-carbaldehydes to synthesize other valuable heterocycles is described. These carbaldehydes are obtained in excelle
- Rocha, Djenisa H.A.,Batista, Vasco F.,Balsa, Emanuel J.F.,Pinto, Diana C.G.A.,Silva, Artur M.S.
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- Synthesis of three new donor- acceptor [4] dendralenes
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Three new donor - acceptor [4] dendralene compounds have been synthesized. Wittig reaction was used for the preparation of first two compounds and third one by Knoevehagel condensation. Their mass was calculated by APCI mass spectra which are in good agre
- Talpur, Mir Munsif Ali,Pirzada, Tajnees,Skabara, Peter,Westgate, Thomas,Shah, Mohammad Raza
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p. 1219 - 1225
(2013/09/23)
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- Protective group-free synthesis of 3,4-dihydroxytetrahydrofurans from carbohydrates: Formal total synthesis of sphydrofuran
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Carbohydrates are taking a more prominent role in chemistry as an environmentally benign chemical feedstock. However, major efforts are still required to convert unprotected carbohydrates into high-value building blocks. We have investigated the protectiv
- Van Kalkeren, Henri A.,Van Rootselaar, Stefan,Haasjes, Frank S.,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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p. 30 - 37,8
(2012/12/12)
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- P-nitrobenzyl triphenyl phosphonium ylide as new initiator in polymerization of ethylacrylate
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1,2-Dipolar compound containing phosphorus ylide (p-NBTPY) initiated radical polymerization of ethylacrylate in dioxane yielding syndiotactic polyethylacrylate, as evidenced by FTIR and 1H NMR. It was investigated dilatometrically at 65 ± 0.1 °C for 1 h under nitrogen atmosphere. The kinetic expression is Rp ∞ [I]0.4 [M] 1.2. The system follows non-ideal kinetics because of primary radical termination. The activation energy and kp 2/kt were calculated as 53 kJ/mol and 0.15×10-2 mol L-1 s-1, respectively. Thermal properties of polymer have been established with the help of DSC and TGA technique. The polymer has been characterized by MALDI-TOF. The absence of phosphorus in polymer matrix is confirmed from the scanning electron microscopy. The initiation is brought about by phenyl radical as evidenced from six hyperfine lines in electron spin resonance spectrum.
- Prajapati, Kiran,Varshney, Anuradha
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p. 2361 - 2368
(2012/02/01)
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- 1-[(E)-2-arylethenyl]-2,2-diphenylcyclopropanes: Kinetics and mechanism of rearrangement to cyclopentenes
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Kinetic measurements for the thermal rearrangement of 2,2-diphenyl-1-[(E)- styryl]cyclopropane (22a) to 3,4,4-triphenylcyclopent-1-ene (23a) in decalin furnished ΔHρm{{-{isom}^{ne }}}$=31.0±1.2kcal mol-1 and ΔSρm{{-{isom}^{ne }}}$=-6. 0±2.6e.u. The lowering of ΔHa‰ by 20kcal mol-1, compared with the rearrangement of the vinylcyclopropane parent, is ascribed to the stabilization of a transition structure (TS) with allylic diradical character. The racemization of (+)-(S)-22a proceeds with ΔHρm{{-{rac}^{ne }}}$=28.2±0.8kcal mol -1 and ΔSρm{{-{rac}^{ne }}}$=-5±2e.u., and is at 150° 106 times faster than the rearrangement. Seven further 1-(2-arylethenyl)-2,2-diphenylcyclopropanes 22, (E)- and (Z)-isomers, were synthesized and characterized. The (E)-compounds showed only modest substituent influence in their krac (at 119.4°) and kisom (at 159.3°) values. The lack of solvent dependence of rate opposes charge separation in the TS, but a linear relation of log krac with log p.r.f., i.e., partial rate factors of radical phenylations of ArH, agrees with a diradical TS. The ring-opening of the preponderant s-trans-conformation of 22 gives rise to the 1-exo-phenylallyl radical 26 that bears the diphenylethyl radical in 3-exo-position, and is responsible for racemization. The 1-exo-3-endo-substituted allylic diradical 27 arises from the minor s-gauche-conformation of 22 and is capable of closing the three- or the five-membered ring, 22 or 23, respectively. The discussion centers on the question whether the allylic diradical is an intermediate or merely a TS. Quantum-chemical calculations by Houk etal. (1997) for the parent vinylcyclopropane reveal the lack of an intermediate. Can the conjugation of the allylic diradical with three Ph groups carve the well of an intermediate? Copyright
- Mulzer, Johann,Huisgen, Rolf,Arion, Vladimir,Sustmann, Reiner
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experimental part
p. 1359 - 1388
(2011/10/09)
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- Wittig reactions of chromone-3-carboxaldehydes with benzylidenetriphenyl phosphoranes: A new synthesis of 3-styrylchromones
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An efficient route to 3-styrylchromones has been developed and applied to syntheses of several new derivatives. Wittig reactions of chromone-3- carboxaldehydes with some benzylic ylides gave a diastereomeric mixture of (E) and (Z)-3-styrylchromones that a
- Sandulache, Angela,Silva, Artur M. S.,Pinto, Diana C. G. A.,Almeida, Lucia M. P. M.,Cavaleiro, Jose A. S.
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p. 1592 - 1598
(2007/10/03)
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- A convenient synthesis of d-Sotalol
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Synthesis of d-Nifenalol and d-Sotalol has been achieved in high enantiomeric purity via Sharpless asymmetric dihydroxylation of 4-nitrostyrene followed by the regiospecific opening of chiral cyclic sulfate with isopropylamine.
- Phukan,Jagtap,Sudalai
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p. 950 - 953
(2007/10/03)
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- Syntheses of terminally substituted conjugated polyenes
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Polyenes and polyenals of the carotenoid type with five, nine and thirteen conjugated double bonds and a variety of terminally substituents like benzenes, naphthalenes, anthracenes, and tetraphenyl porphyrines are synthesized via Wittig reactions starting from crocetin dialdehyde or 2,7-dimethyloctatriendial, respectively. The characterization, and in most cases also the separation, of the E/Z-isomers of the polyenes is possible.
- Effenberger,Schlosser
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p. 1085 - 1094
(2007/10/02)
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- A Facile and New Route for the Synthesis of Substituted 1,2-Dithiafulvenes Using Phosphonium Ylides
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A wide variety of 6-aryl-5-phenyl-1,2-dithiafulvenes and 6-aroyl-5-phenyl-1,2-dithiafulvenes (4) have been synthesized by the interaction of 5-phenyl-1,2-dithiol-3-one (3a) and phosphonium ylides (2).The synthesis of these dithiafulvenes has also been car
- Gupta, K. C.,Saxena, B. K.,Pathak, P. K.
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p. 312 - 314
(2007/10/02)
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- 3-(Substituted) vinyl cephalosporins
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New 3-(substituted) vinyl cephalosporin compounds, e.g., 3-(2'-ethoxycarbonylvinyl)-7-phenoxyacetamido-3-cephem-4-carboxylic acid, which are useful as antibiotics, and 3-(substituted) vinyl cephalosporin compounds which are useful as intermediates in preparing antibiotic substances.
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