Search results for "DERIVATIVES"

Synthesis and biological evaluation of new 1,2,4-oxadiazole derivatives of Topsentin

Three 2,5-dialkoxy-1,4-diethynylbenzene derivatives

2008

2,5-Dieth­oxy-1,4-bis­[(trimethyl­silyl)ethyn­yl]benzene, C20H30O2Si2, (I), constitutes one of the first structurally characterized examples of a family of compounds, viz. the 2,5-dialk­oxy-1,4-bis­[(trimethyl­silyl)ethyn­yl]benzene derivatives, used in the preparation of oligo(phenyl­ene­ethynylene)s via Pd/Cu-catalysed cross-coupling. 2,5-Dieth­oxy-1,4-diethynylbenzene, C14H14O2, (II), results from protodesilylation of (I). 1,4-Diethynyl-2,5-bis­(hept­yloxy)benzene, C24H34O2, (III), is a long alk­yloxy chain analogue of (II). The molecules of compounds (I)–(III) are located on sites with crystallographic inversion symmetry. The large substituents either in the alkynyl group or in the benz…

Determination of Pyrrole Derivatives and Hydroxyproline with 4-(Dimethylamino)benzaldehyde in a Micellar Medium

1994

Abstract The spectrophotometric determination of pyrrole derivatives and hydroxyproline with 4-(dimethylamino)benzaldehyde (Ehrlich's reagent) in a sodium dodecyl sulphate micellar medium is studied. Pyrrole and pyrrole-2-carboxylic acid were used as model compounds for the optimization of the procedure. In the micellar medium with 0.2 M HCl at 90° C, pyrrole reacts in 15 min, whereas a HCl concentration larger than 5 M is required in the absence of the surfactant. The sensitivity increases from 1.3 to 5.6-fold with respect to the use of a non-micellar medium, for some pyrrole derivatives. The procedure is applied to the determination of hydroxyproline in meat samples.

Controlled Self-Assembly of Electron Donor Nanotubes

2009

We employ a combination of urea-urea hydrogen bonds and pi-pi stacking interactions to obtain soluble self-assembled nanotubes decorated with electron-donor TTF derivatives on the periphery. We have investigated the structure and stability of the nanotubes with a combination of experiments and high-level DFT calculations. We also demonstrate that the association process can be controlled by changes in the hydrogen-bonding ability of the solvent and electrochemically.

Pyrrolomycins as potential anti-staphylococcal biofilms agents

2010

With the goal of discovering new anti-infective agents active against microbial biofilms, this investigation focused on some natural pyrrolomycins, a family of halogenated pyrrole antibiotics. In this study the anti-staphylococcal biofilm activity of pyrrolomycins C, D, F1, F2a, F2b, F3 and of the synthesized related compounds I, II, III were investigated. The susceptibility of six staphylococcal biofilms was determined by methyltiazotetrazolium staining. Most of the compounds were active at concentrations of 1.5 microg ml(-1) with significant inhibition percentages. A few of the compounds were active at the lowest screening concentration of 0.045 microg ml(-1). The population log reduction…

The Risk Premium and the Esscher Transform in Power Markets

2012

In power markets one frequently encounters a risk premium being positive in the short end of the forward curve, and negative in the long end. Economically it has been argued that the positive premium is reflecting retailers aversion for spike risk, wheras in the long end of the forward curve the hedging pressure kicks in as in other commodity markets. Mathematically, forward prices are expressed as risk-neutral expectations of the spot at delivery. We apply the Esscher transform on power spot models based on mean-reverting processes driven by independent increment (time-inhomogeneous Levy) processes. It is shown that the Esscher transform is yielding a change of mean-reversion level. Moreov…

Syntheses of Four Enantiomers of 2,3-Diendo- and 3-Endo-aminobicyclo[2.2.2]oct-5-ene-2-exo-carboxylic Acid and Their Saturated Analogues

2013

Abstract: Ethyl 2,3- diendo -3-aminobicyclo[2.2.2]oct- 5-ene-2-carboxylate ((±)- 1 ) was resolved with O , O '-dibenzoyltartaric acid via diastere omeric salt formation. The efficient synthesis of the enantiomers of 2,3- diendo -3-aminobicyclo[2.2.2]oct- 5-ene-2-carboxylic acid ((+)- 7 and (–)- 7 ), 3- endo -aminobicyclo[2.2.2]oct-5-ene-2- exo -carboxylic acid ((+)- 5 and (–)- 5 ), cis - and trans -3-aminobicyclo[2.2.2]octa ne-2-carboxylic acid ((+)- 6 , (–)- 6 , (+)- 8 and (–)- 8 ) was achieved via isomerization, hydrogenation and hydrolysis of the corresponding esters (–)- 1 and (+)- 1 . The stereochemistry and relative configurations of the synthesized compounds were determined by NMR sp…

Nitramino, NRNO2 (R = H, CH3), as a substituent.13C and15N NMR spectroscopic study of nitraminobenzenes and -pyridines

1993

In order to clarify the special properties of the aryl-bound nitramino substituent NRNO 2 (R=H, CH 3 ), 13 C and 15 N NMR spectra of six nitraminobenzenes and nine nitraminopyridines were measured in DMSO-d 6 and their chemical shifts assigned. 1 H NMr chemical shifts and spin-spin coupling constants of all the compounds were also determined. In contrast to the behaviour of nitropyridines or -benzenes studied previously, most of the present compounds gave very broad 17 O NMR lines even at elevated temperatures and their 17 O NMR data were not useful for any reliable conclusions

Annelated pyrrolo-pyrimidines from amino-cyanopyrroles and BMMAs as leads for new DNA-interactive ring systems.

2005

The efficient one-pot synthesis of several new tricyclic systems of type 1 and 2, obtained from the reaction of substituted 2-amino-3-cyanopyrroles and 3-amino-4-cyanopyrroles with BMMAs, is reported. The duration and yields of the reaction strongly depend on the reactivity of the starting pyrrole and on the size of the ring to be formed. Mechanist features of the reaction were investigated and proposed by studying also the reactivity of a 3-aminopyrrole-2,4-dicyano substituted. The method reported represents the first example of the use of BMMA reagents in combination with pyrrole derivatives and allows an easy and versatile entry to a large number of hitherto unknown pyrrolo-pyrimidines f…

Enlarging the family of ferrocenylphosphine dinuclear rhodium complexes: synthesis and X-ray structure of a novel “A-frame”-type trimetallic Rh/Fe/Rh…

2004

Abstract The symmetrically substituted ligand 1,1 ′ -bis[di(5-methyl-2-furyl)phosphino]ferrocene ( 1 ) has been obtained from the bromophosphine BrP(Fu Me ) 2 and the dilithioferrocene/TMEDA adduct. The quantitative addition of this ferrocene derivative to the tetracarbonyl dimer [(CO) 4 Rh 2 {μ-(S t Bu) 2 }] leads, through decarbonylation, to the dinuclear rhodium complex [(CO) 2 Rh 2 {μ-(S t Bu) 2 }{μ- P , P -Fc[P(Fu Me ) 2 ] 2 }] ( 2 ) in high yield. A X-ray structure [ orthorhombic , space group P 2 1 2 1 2 1 ; a =11.2982(2) A, b =13.3165(3) A, c =27.2687(7) A] and the solution multinuclear NMR characterization are reported, which show that the rare “quasi-closed bridging” A-frame struc…