Presence Of NCs Research Articles

Silver-Catalyzed Chlorocyclization for the Synthesis of 3-Chloro-2H-chromenes.

A silver-catalyzed chlorocyclization reaction of aryl 3-aryl-2-propyn-1-yl ethers in the presence of NCS under darkness was accomplished, which provides a straightforward and efficient access to 3-chloro-2H-chromenes.

Diversity-Oriented Synthesis of 1,2,4-Triazols, 1,3,4-Thiadiazols, and 1,3,4-Selenadiazoles from N-Tosylhydrazones.

The diversity-oriented synthesis of 1,2,4-triazols, 1,3,4-thiadiazols, and 1,3,4-selenadiazoles from N-tosylhydrazones was developed, and the reactions were general for a wide range of substrates, in which NH2CN, KOCN, KSCN, and KSeCN were used as odorless sources. Two different pathways were proposed, and N-tosylhydrazonoyl chlorides were formed in situ in the presence of NCS.

Direct halogenation of the C1[sbnd]H bond in pyrrolo[1,2–a]quinoxalines

Although pyrrolo[1,2–a]quinoxalines are important in pharmaceutical research and organic synthesis, diversification of these compounds is still limited. Herein we have developed a method for the selective chlorination of the C1H bond in 4-aryl pyrrolo[1,2–a]quinoxalines. The reactions proceeded in the presence of NCS as a chlorinating agent, a catalytic amount of DMSO, and CHCl3 as the solvent. Various functional groups including fluoro, chloro, and methylthio were compatible with the reaction conditions. Heterocycles located at the C4 positions of pyrrolo[1,2–a]quinoxalines such as furan, thiophene, or pyridine were also compatible with the reaction conditions. The bromination of pyrrolo[1,2–a]quinoxalines was successful in the presence of CuBr2 as a brominating agent, K2S2O8 as an oxidant, and toluene as the solvent.

Anion-directed assemblies of Cu(II) mono, di, and poly-nuclear coordination compounds with a 32-membered azacrown ligand: Synthesis, characterisation and crystal structures

A novel 32-membered azacrown ligand L was synthesized from the [2 + 2] condensation between 2-[3-(2-formylphenoxy)-2-hydroxy propoxy]benzaldehyde and 1,2-diaminopropane by following in situ reduction. Three metal-organic coordination compounds [CuL(NCS)]NO3·CH3OH (1), [Cu2L(CH3COO)4].0.5H2O (2), and [CuL(μ-Cl)(NO3)]n.2nCH3CN (3), were prepared from reaction of L with copper(II) salts containing different anions. Depending on the reaction controlling factor, i.e. NCS−, CH3COO−, NO3−, and Cl− anions, mono, di and polynuclear metal-organic coordination compounds were constructed. Complexes were characterized by spectroscopic methods and single crystal X-ray diffraction. Crystal structures indicate that L in presence of NCS− and Cu(NO3)2·3H2O forms mononuclear complex 1. Dinuclear complex 2 was formed by the reaction of L in presence of Cu(CH3COO)2·2H2O. Reaction of Cu(NO3)2·3H2O and CuCl2·3H2O with L give rise complex 3 which is a 1-dimensional coordination polymer. The coordination polymer constructed from distorted octahedron shaped copper nucleus that are exomacrocylic in which two Cl atoms serve as bridge. Potentially decadentate ligand, L, with four N- and six O-donor sites in presence of Cu(II) salts reacts only with its N-donors. Complexes 1 and 3, both, are crystalized in a centrosymmetric space group P21/c and dinuclear complex 2 is crystalized in a polar space group P21.

Synthesis and Biological Evaluation of Novel Hybrid Molecules Containing Purine, Coumarin and Isoxazoline or Isoxazole Moieties.

Introduction:The 1,3-dipolar cycloaddition reactions of nitrile oxides formed in situ (in the presence of NCS and Et3N) from the oximes of (purin-9-yl)acetaldehyde or (coumarinyloxy)acetaldehyde with allyloxycoumarins or 9-allylpurines, respectively resulted in 3,5-disubstituted isoxazolines. The similar reactions of propargyloxycoumarins or 9-propargylpurines led to 3,5-disubstituted isoxazoles by treatment with PIDA and catalytic amount of TFA.Methods:The new compounds were tested in vitro as antioxidant agents and inhibitors of soybean lipoxygenase LO, AChE and MAO-B.Results:The majority of the compounds showed significant hydroxyl radical scavenging activity. Compounds 4k and 4n presented LO inhibitory activity.Conclusion:Compound 13e presents an antioxidant significant profile combining anti-LO, anti-AChE and anti-MAO-B activities.

A new synthesis of functionalized dialkyl maleate and fumarate derivatives by addition of amines to dialkyl acetylenedicarboxylates in the presence of NBS or NCS

In this new three-component reaction, maleate and fumarate derivatives produced from amine and dialkyl acetylenedicarboxylate in the presence of NCS or NBS at room temperature in good yields.

A new synthesis of S-aryl uracils from aryl thiols and 6-amino uracils in the presence of NCS.

Sulfenylchloride intermediates generated from the reaction of aryl thiols with N-chlorosuccinimide were trapped by 6-amino uracil derivatives to yield 6-amino-5-(arylthio)-pyrimidine-2,4(1H,3H)-dione compounds at room temperature.

Fe-Promoted Chlorobenzylation of Terminal Alkynes through Benzylic C(sp(3))-H Bond Functionalization.

A chlorobenzylation of terminal alkynes through Fe(II)-promoted benzylic C(sp(3))-H bond functionalization in the presence of NCS as a chloride source was developed. Compared with previous methods to prepare polysubstituted alkenyl halides, the presented procedure provides an efficient alternative with high atom and step economy under mild conditions. The transformation was established to proceed through a single-electron transfer (SET) process with benzyl cations as key intermediates.

Coordination Chemistry of Homoleptic Actinide(IV)-Thiocyanate Complexes.

The synthesis, X-ray crystal structure, vibrational and optical spectroscopy for the eight-coordinate thiocyanate compounds, [Et4 N]4 [Pu(IV) (NCS)8 ], [Et4 N]4 [Th(IV) (NCS)8 ], and [Et4 N]4 [Ce(III) (NCS)7 (H2 O)] are reported. Thiocyanate was found to rapidly reduce plutonium to Pu(III) in acidic solutions (pH<1) in the presence of NCS(-) . The optical spectrum of [Et4 N][SCN] containing Pu(III) solution was indistinguishable from that of aquated Pu(III) suggesting that inner-sphere complexation with [Et4 N][SCN] does not occur in water. However, upon concentration, the homoleptic thiocyanate complex [Et4 N]4 [Pu(IV) (NCS)8 ] was crystallized when a large excess of [Et4 N][NCS] was present. This compound, along with its U(IV) analogue, maintains inner-sphere thiocyanate coordination in acetonitrile based on the observation of intense ligand-to-metal charge-transfer bands. Spectroscopic and crystallographic data do not support the interaction of the metal orbitals with the ligand π system, but support an enhanced An(IV) -NCS interaction, as the Lewis acidity of the metal ion increases from Th to Pu.

Instigation and monitoring of inertial cavitation from nanoscale particles using a diagnostic imaging platform and passive acoustic mapping

Inertial cavitation nucleated by microbubble contrast agents has been recently shown to enhance extravasation and improve the distribution of anti-cancer agents during ultrasound (US)-enhanced delivery. However, microbubbles require frequent replenishment due to their rapid clearance and destruction upon US exposure and are unable to extravasate into tumor tissue due to their large size. A new generation of gas-stabilizing polymeric cup-shaped nanoparticles, or “nanocups” (NCs), have been formulated to a size that enables exploitation of the enhanced permeability and retention effect for intratumoral accumulation. NCs provide sustained inertial cavitation, as characterized by broadband emissions, at peak rarefactional pressures readily achievable by diagnostic ultrasound systems. This enables the use of a single low-cost system for B-mode treatment guidance, instigation of cavitation, and real-time passive acoustic mapping (PAM) of the location and extent of cavitation activity during therapy. The significant lowering of the inertial cavitation threshold in the presence of NCs as characterized by PAM is first quantified in-vitro. In-vivo and ex-vivo results in xenograft-implanted tumor bearing mice further evidence the strong presence of inertial cavitation detectable in the tumor at diagnostic levels of US intensity, as confirmed by PAM images overlaid on B-mode in real-time.

Fluorometric sensing of thiocyanate ions and competitive binding of anions in a family of CdII complexes of a phenol based ligand showing diverse structures

A family of central phenoxido and terminal alcohol bound Cd2 complexes have been synthesized and crystallographically characterized. Reaction condition and anion coordination (NO3−, NCS− and N3−) dependent changeable structures have been identified in the four complexes 1–4 following varying coordination of the binucleating Schiff base ligand H3bemp (2,6-bis[(2-hydroxy ethylimino)-methyl]-4-methyl phenol) to cadmium(II) ions. These complexes have been characterized by X-ray crystallography, spectroscopic and analytical techniques. During the formation of 2 and 3, the phenoxido bridging unit of H3bemp is transformed to non-bridging modes of binding following the coordination of NO3− and NCS−, while changing one imine function on each ligand to the zwitterionic form, generated through a kind of acid–base reaction for metal ion coordination. The H3bemp molecule registers as a highly selective and sensitive fluorescent probe for Cd2+ in a PBS buffer (5mM in pH=7.1) at 25°C. In the presence of Cd2+, the increase in fluorescence intensity is accounted for by the formation of [Cd2(H2bemp)2](NO3)2 (1) in solution. The fluorescence quantum yield of H3bemp is 0.201, and it increases more than 4-fold (0.851) in the presence of the cadmium ion. In presence of NCS−, complex 1 showed coordination induced fluorescence enhancement, whereas NO3− and N3− anions quench the emission intensities significantly.

125 ISOLATION OF MULTILINEAGE STEM CELLS FROM THE PORCINE MAMMARY FAT PAD

Porcine mammary tissue is a dynamic system that undergoes multiple cycles of growth, differentiation, and regression during the life cycle of a female; however, the mechanisms of mammary morphogenesis are not fully understood. The current hypothesis suggests that epithelial stem cells in the terminal end buds interact with surrounding epithelial and stromal cells during mammary tissue development and regeneration. Because the mammary gland of the virgin animal consists largely of a pad of adipose tissue, we propose that adipose-derived stem cells from the mammary fat pad (MFP) may also play a role in the regeneration process. Therefore, the objective of this experiment was to determine whether multilineage stem cells are present in the MFP of gilts. Adipose tissue from the MFP and back fat (BF) from the loin region were harvested from six nulliparous, cycling Yorkshire gilts, approximately 16 mo of age. Methods for isolation of adipose-derived stem cells were modified from those of Malusky and Wheeler (2004; International Society for Stem Cell Research, Proceedings 2nd Annual Meeting, abstr. 248:124). Presumptive stem cells isolated from each tissue type were maintained in vitro in DMEM supplemented with either 10% newborn calf serum (NCS; Rep 1 and 2) or 10% fetal calf serum (Rep 3). BF and MFP cell types formed colonies of fibroblast-like cells within 3 to 5 d. Growth characteristics are shown in Table 1. When the cells were 80% confluent, they were trypsinized and reseeded into 75-cm2 flasks. When cultured in the presence of NCS, both cell types had a progressive decrease in viability, and these cultures could not be maintained past Passage 4. Differentiation of both cell types (Passage 1) into adipogenic, myogenic, and osteogenic lineages are currently underway. Based on morphological evaluations, both cell types are able to differentiate into the aforementioned lineages; however, differentiation of MFP-derived cells occurred at a slower rate and was less pronounced than that of BF-derived cells. These preliminary findings suggest that the MFP likely contains a population of multipotent stem cells; however, at this time, it is not possible to make meaningful statistical comparisons. Further experiments are needed to fully characterize these cells and determine their role in mammary gland morphogenesis. Table 1. Growth of porcine adipose-derived stem cells obtained from the BF or from the MFP This study was partially supported by the Council for Food and Agricultural Research (C-FAR) Sentinel Program and USDA Multistate Project (W-1171).

The Factors Governing the Coordination Number in the Anion Derivatives of Carbonic Anhydrase

Abstract The electronic and 1H NMR spectra of cobalt(II)-substituted carbonic anhydrase in the presence of NCS−, N3 − and NCO− on one side and CH3COO−, ClO4 − and NO3 − on the other are presented here and discussed in the light of the available X-ray data on two kinds of inhibitors. The aim of this article is to focus on the factors which determine the coordination number of the inhibitor derivatives. It is proposed that the hydrophobic or the hydrophilic character of the inhibitors provide an important contribution to the energy balance between four and five coordination.

Thiocyanate Ion Promoted E ⇌ Z Isomerization of a‐Bromo‐β,β‐Diactivated Electrophilic Olefins: An Apparent High Nucleofugality of NCS−

Abstract(E)‐β‐Chloro‐α‐phenylcinnamaldehyde and (E)‐ and (Z)‐methyl α‐tert‐butoxycarbonyl‐p‐nitro‐β‐bromocinnamates in the presence of NCS− ion in acetonitrile undergo an (E) ⇌ (Z) isomerization which is faster than the vinylic substitution. (E)‐ and (Z)‐methyl α‐cyano‐β‐mesyloxy‐ (and β‐chloro‐) p‐nitrocinnamates undergo substitution under similar conditions without preceding isomerization. MO calculations gave the energy differences between the eclipsed and the perpendicular conformers of carbanions −CH2CH2X and (NC)2ČH2X (X = Cl, NCS). These rotational barriers denote the hyperconjugation stabilization energy resulting from interaction of the C‐X bond and the 2p(C−) orbital. Both HCA values are high, those for X = Cl being 15–20% higher than for X = NCS. The limited literature data on the nucleofugality of NCS− suggests that it can have a nucleofugality which is not much lower than that of Cl− or Br−. Consequently, NCS−‐catalyzed isomerizations of electrophilic vinyl chlorides and bromides, which involve a 180° internal rotation followed by a faster expulsion of NCS− than of Cl− from the initially formed intermediate carbanion Y'Y−C‐C(R)(Cl)SCN, are not unreasonable, especially if solvation, which was not included in the calculations, plays an important role in the nucleofuge expulsion process.

Synthesis and Physicochemical Investigation of Nickel (II). Complexes with salicylaldehyde S‐methylthiosemicarbazone

AbstractSalicylaldehyde S‐methylthiosemicarbazone (H2L) in the presence of ClO4– forms with NiII the paramagnetic octahedral bis(ligand) chelate complexes while in the presence of NCS−, CH3COO−, Py and γ‐Pic it gives diamagnetic square planar mono(ligand) chelate complexes. In the paramagnetic complexes H2L is coordinated as a neutral molecule (H2L) and monoanion (HL−), and in diamagnetic ones only as a monoanion, except the complex obtained in the presence of CH3COO−, where it is coordinated as a dianion (L2−). The last form of the ligand is the result of deprotonation, besides OH‐, the NH2‐group. The complexes have been characterized by elemental analysis, magnetic measurements, i.r. and diffuse‐reflection spectra, molar conductivity and TG analysis.