Chloride Derivatives Research Articles

Resonance Balance Shift in Stacks of Delocalized Singlet Biradicals

Recently we succeeded in the isolation of delocalized singlet biradicals utilizing the spin-delocalizing character of the phenalenyl radical. We demonstrated that the singlet biradical 1 has strong spin–spin interactions between molecules through the overlap of phenalenyl rings in the onedimensional (1D) chain even though the closed-shell Kekul structure 1 can be drawn as a resonance contributor (Scheme 1). Huang and Kertesz gave further insight into the spin–spin interactions from a theroretical point of view and showed that the spin–spin interaction between the molecules was predicted to be stronger than that within the molecule. These experimental and theoretical findings are associated with very fundamental issues: Do delocalized singlet biradicals actually have open-shell character? Are the electrons coupled within a molecule involved in covalent bonding between molecules? In this study we will demonstrate that intraand intermolecular spin–spin interactions strongly correlate and can be altered in magnitude by an applied external field. Our proposal is based on the experimentally determined molecular structure of 2, a temperature-dependent reflection spectrum of 2, and a pressuredependent reflection spectrum of 1. Methyl groups at the 2and 10-positions in 2, where the frontier molecular orbital has very small coefficients, are expected to alter the distance between the overlapping phenalenyl rings with respect to the analogous separation in 1, and as a result, the magnitude of the intermolecular spin–spin interaction should be affected. The synthesis of 2 is outlined in Scheme 2. The 3,10and 3,11-bis(bromomethyl) compounds 3 were synthesized according to the previously reported procedures. The individual isomers were not isolated because both were expected to lead to the single compound 2. Bis(2-methylpropionic acid) derivatives 5 were obtained in three steps by standard methods. Friedel–Crafts cyclization of the acyl chloride derivatives of 5 with AlCl3 afforded diketones 6. These were reduced with NaBH4 and subsequently dehydrated with a catalytic amount of p-toluenesulfonic acid to afford the dihydro compounds 8. Dehydrogenation of 8 with p-chloranil afforded the hydrocarbon 2 as green prisms. Compound 2 was found to be stable in the solid state at room temperature. The small HOMO–LUMO gap of 2, which is an essential factor for a singlet biradical electronic structure, was confirmed by electrochemical and optical methods. The cyclic voltammogram of 2 shows four reversible redox waves: E 2 = + 0.51, E 1 =+ 0.11, E red 1 = 1.09, and E 2 = 1.62 (V vs. ferrocene/ferrocenium couple (Fc/Fc), see Figure S1 in the Supporting Information), which led to an electrochemical HOMO–LUMO gap of 1.20 eV. The electronic absorption spectrum of 2 in CH2Cl2 shows an intense low-energy band at 756 nm (13200 cm = 1.64 eV, e= 115000, f= 0.605, see Scheme 1. Resonance structures of 1 and 2. The arrows in the biradical structure represent antiparallel spins.

Determination of the formation constant for the inclusion complex between Lanthanide ions and Dansyl chloride derivative by fluorescence spectroscopy: Theoretical and experimental investigation

In this paper, a sensitive, easy, efficient, and suitable method for the calculation of K f values of complexation between one derivative of Dansyl chloride [5-(dimethylamino) naphthalene-1-sulfonyl 4-phenylsemicarbazide] (DMNP) and Lanthanide(III) (Ln) ions is proposed, using both spectrofluorometric and spectrophotometric methods. Determination of K f showed that DMNP was mostly selective towards the erbium (III) ion. The validity of the method was also confirmed calculating the Stern–Volmer fluorescence quenching constants ( K sv) that resulted in the same consequence, obtained by calculating the K f of complexation values. In addition, the UV–vis spectroscopy was applied for the determination of K f only for the Ln ions that had interactions with DMNP. Finally, the DFT studies were done on Er 3+ and the DMNP complex for distinguishing the active sites and estimating the pair wise interaction energy. It can be concluded that this derivative of Dansyl chloride with inherent high fluorescence intensity is a suitable reagent for the selective determination of the Er 3+ ion which can be used in constructing selective Er 3+ sensors.

Binuclear Platinum(IV) Complexes with Bridging Amidoalkyl Groups and Their Self-Assembly through Hydrogen Bonding

Oxidative addition of the reagents {4-BrCH2C6H4-(CH2)x-C(═O)NH-(CH2)y}2Z to [PtMe2(bu2bipy)], bu2bipy = 4,4′-di-t-butyl-2,2′-bipyridine, gave the corresponding diplatinum(IV) complexes [{PtBrMe2(bu2bipy)-4-CH2C6H4-(CH2)x-C(═O)NH-(CH2)y}2Z], with Z = o-, m-, or p-C6H4 and x, y = 0 or 1; or Z = 1,2-C2H4 and x = y = 0. The complexes are formed selectively by trans oxidative addition to both platinum(II) centers and contain long bridging alkanediyl ligands containing two amide units in the backbone. Several iodide analogues were prepared by displacement of bromide from the bromoplatinum(IV) complexes by reaction with lithium iodide, and in one case, a chloride derivative was formed by the reaction of a bromoplatinum(IV) complex with solvent carbon tetrachloride. In the solid state, the compounds undergo self-assembly to form supramolecular polymers, ribbon polymers, or a sheet structure by forming intermolecular hydrogen bonds of the type NH···O═C, NH···BrPt or NH···ClPt.

Heteropolyacid as a New, Green and Recyclable Catalyst for the Synthesis of 2‐Aryl Benzoxazole under Solvent‐Free Conditions

AbstractA simple, convenient and general method has been developed for the synthesis of 2‐arylbenzoxazole via condensation of o‐aminophenols and benzoyl chloride derivatives under solvent‐free conditions in the presence of a catalytic amount of heteropolyacids in good yields.

Synthesis and photopolymerizations of new phosphonated methacrylates from alkyl α‐hydroxymethacrylates and glycidyl methacrylate

AbstractNovel aromatic mono‐ and di(phosphonate) or phosphonic acid monomers for use in dental composites were synthesized. Synthesis of monomer 1a involved three steps: (i) reaction of t‐butyl α‐bromomethacrylate (t‐BuBMA) and Bisphenol A, (ii) conversion to diacid chloride derivative using thionyl chloride, (iii) reaction of diacid chloride with diethyl (2‐hydroxyphenyl) phosphonate. Monomer 2a was synthesized from the reaction of 2‐chloromethacryloyl chloride and diethyl (2‐hydroxyphenyl) phosphonate. Synthesis of monomer 3a involved reaction of glycidyl methacrylate (GMA) with diethyl (2‐hydroxyphenyl) phosphonate. Hydrolysis of the phosphonate groups of monomers 1a and 2a with trimethylsilyl bromide (TMSBr) gave monomers 1b and 2b with phosphonic acid functionality, which is intended to improve binding ability of dental composites. The homopolymerization and copolymerization behaviors of the synthesized monomers with (Bis‐GMA) were investigated using photodifferential scanning calorimetry at 40°C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as photoinitiator. The interaction of the monomer 1b with hydroxyapatite (HAP) was investigated using Fourier transform infrared technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and evaluation of in vitro antiviral activity of 2-[3-(substituted phenyl)-4,5-dihydro-1H-5-pyrazolyl]benzofuran-3-yl chloride derivatives

3-Chlorobenzofuran-2-carbaldehyde was condensed with substituted acetophenone by using the Claisen-Schmidt condensation to obtain 3-(3-chlorobenzofuran-2-yl)-1-(substituted phenyl)-2-propen-1-one (2a-m) which upon further treatment with hydrazine hydrate gave 2-[3-(substituted phenyl)-4,5-dihydro-1H-5- pyrazolyl)benzofuran-3-yl chloride derivatives (3a-m). All the newly synthesized derivatives were evaluated in vitro for cytotoxicity and antiviral activity in Crandell-Rees Feline Kidney cell, human embryonic lung (HEL) cell, HeLa cell and Vero cell cultures against different viruses. Several compounds, i.e. 2f, 2g, 2i, 2m, 3b, 3d, 3g, 3h and 3m proved quite cytotoxic to the host cells (minimum cytotoxic concentration: 1-10 μg/mL). No specific antiviral activity [50% antivirally effective concentration (EC50) ≥ 5-fold lower than the minimum cytototoxic concentration] was observed for any of the compounds.

Caveolin-1 enhances resveratrol-mediated cytotoxicity and transport in a hepatocellular carcinoma model

BackgroundResveratrol (RES), an estrogen analog, is considered as a potential cancer chemo-preventive agent. However, it remains unclear how RES is transported into cells. In this study, we observed that Caveolin-1(CAV1) expression can increase the cytotoxic and pro-apoptotic activity of RES in a dose- and time-dependent manner both in vitro and in vivo in a Hepatocellular Carcinoma animal model.MethodsHigh performance liquid chromatography (HPLC) demonstrated that RES intra-cellular concentration is increased about 2-fold in cells stably expressing CAV1 or CAVM1 (a scaffolding domain (81-101AA)-defective CAV1 mutant) compared to the untransduced human Hepatoblastoma cell line (HepG2) or after transduction with the green fluorescent protein (GFP) control vector. The increased intra-cellular transport of RES was abolished in cells stably expressing CAVM2 (a cholesterol shuttle domain (143-156AA)-defective CAV1 mutant) or CAVRNAi. In order to further characterize CAV1-dependent RES transport, we synthesized RES-dansyl chloride derivatives as fluorescent probes to visualize the transport process, which demonstrated a distribution consistent with that of CAV1 in HepG2 cells.ResultsIn addition, RES endocytosis was not mediated by estrogen receptor (ER) α and β, as suggested by lack of competitive inhibition by estrogen or Tamoxifen. Pathway analysis showed that RES can up-regulate the expression of endogenous CAV1; this activates further the MAPK pathway and caspase-3 expression.DiscussionThis study provides novel insights about the role played by CAV1 in modulating cellular sensitivity to RES through enhancement of its internalization and trafficking.

First Total Synthesis of 4-Methylthio-3-butenyl Glucosinolate

The first total synthesis of 4-methylthio-3-butenyl glucosinolate (MTBG), a natural bioactive compound and a precursor of radish phototropism-regulating substances, was achieved from commercially available 1,4-butanediol. The glucosinolate framework was prepared by coupling of an oximyl chloride derivative and tetraacetyl thioglucose. A methylthio group was introduced to the framework by a Wittig reaction between triphenylphosphonium thiomethylmethylide and an aldehyde intermediate of glucosinolate. The synthetic route should facilitate preparation of various derivatives needed for probe synthesis based on MTBG.

Ethyl 5-chloro-2-oxopent-3-ynoate, a new acetylenic dienophile in the Diels-Alder reactions

The lithium derivative of propargyl chloride reacts with diethyl oxalate to give ethyl 5-chloro-2-oxopent-3-ynoate. Under mild conditions, this ester undergoes Diels-Alder reactions with conjugated dienes of various structure. The adducts formed from five-membered cyclic dienes exist as stable enols and the adducts from cyclohexadiene and 2,3-dimethylbuta-1,3-diene exist in the keto form.

Unexpected reversible nitrogen atom transfer in the synthesis of polysubstituted imides and 7-aza-hexahydroindolones via enaminonitrile γ-lactams

An effective route to novel polysubstituted imides is described, which involves the reaction of enaminonitrile γ-lactams derived from N-alkylated α-bromoacetamides and malononitrile with acryloyl chloride derivatives. This preceded via a sequence 1,4-addition-intramolecular peptidic coupling and a γ-lactam hydrolysis in a one ‘pot-procedure’. These imides were regioselectively reduced into corresponding N-acyliminium precursors, which subsequently submitted to an intramolecular aza-cyclization in acidic medium to provide novel 7-hexahydro-aza-indoles.

Well-defined hydrocarbon soluble strontium fluoride and chloride complexes of composition [LSr(thf)(μ-F)2Sr(thf)2L] and [LSr(thf)(μ-Cl)2Sr(thf)2L

Reaction of LSrN(SiMe(3))(2)(thf) (L = CH(CMe-2,6-i-Pr(2)C(6)H(3)N)(2)) with Me(3)SnF and LAlCl(Me), respectively, gave the first example of a strontium mono fluoride complex [LSr(thf)(mu-F)(2)Sr(thf)(2)L] and the corresponding chloride derivative [LSr(thf)(mu-Cl)(2)Sr(thf)(2)L] .

The Regio- and Stereo-Selective Formation of Allylic Chlorides During the Overman Rearrangement of Trichloroacetimidates Derived from Certain Brominated Conduritols

Microwave irradiation of imidate 2 at 165°C affords a ~3:1 mixture of the Overman rearrangement product 3 and the allylic chloride 4 (83% combined yield). Under the same conditions the deoxy-conduritol 6 gives a comparable mixture of compounds 7 and 8. The single-crystal X-ray structure of a derivative of chloride 8 is reported together with a mechanism that accounts for the selective formation of this compound and congener 4.

Synthesis and screening for analgesic and anti-inflammatory activities of some novel amino acid-containing bicyclo compounds

Diazabicyclo[4.3.1]decane derivatives are well known opioid receptor ligands, hence, we have developed a novel and simple method for the synthesis of 3, 4-diphenyl-2,5-diaza-bicyclo[4.3.1]deca-1(9),2,4,6(10),7-pentaene- 8-carbonyl chloride derivatives containing amino acid moieties. The compounds were structurally conÞ rmed with the help of TLC, IR, NMR, and LCMS spectra. All the title compounds were screened for analgesic activity by using the tail-s ick method and for anti-ins ammatory activity by using the carrageenan-induced paw edema method using diclofenac sodium as a standard. Key words: Amino acids, analgesic- anti-ins ammatory activity, 2, 5-diaza bicyclo [4.3.1] compounds.

Group 4 metal complexes bearing new tridentate (NNO) ligands: Benzyl migration and formation of unusual C–C coupled products

Abstract Group 4 metal complexes bearing new phenoxy(benzimidazolyl)-imine, -amine and -amide ligands have been synthesized. A series of metal chloride derivatives has been prepared via treatment of MCl4(THF)2 (M = Ti, Zr, Hf) with the in situ generated sodium salt of the (benzimidazolyl)imine phenol 1. Reaction of the pro-ligand 2 with TiCl4(THF)2 afforded the corresponding complex 8 in which the amine proton remains bound to the nitrogen donor. Benzyl complexes of zirconium and hafnium were synthesized via treatment of pro-ligands 1 and 2 with M(CH2Ph)4 precursors. The complexes [NNO]M(CH2Ph)3 (6 M = Zr, 7 M = Hf) were found to undergo benzyl migration from the metal centre to the imine carbon of the ligand backbone giving complexes 11 and 12; the migration follows first order kinetics. The reaction of 1 with Ti(NMe2)4 led to the formation of an unusual C–C coupled product in which a new piperazine ring has formed. Complexes 11 and 12 undergo related transformations, leading to analogous C–C coupled products which were characterized by X-ray crystallography. Deuterium labelling experiments were carried out to determine the mechanistic pathway of the reactions. Chloride and benzyl complexes 3–12 were screened as pre-catalysts for olefin polymerization.

Selective Catalytic Dimerization of Neohexene by [Cp*Ti(NPtBu3)Me][B(C6F5)4

The known titanium alkyl cation [Cp*Ti(NPtBu3)Me][B(C6F5)4], supported by a bulky phosphinimide donor, was found to react with 3 equiv of 3,3-dimethyl-1-butene (neohexene) to generate another alkyl cation in which the alkyl group is derived from two dimerized equivalents of the substrate olefin. This species, 1, was characterized in detail by spectroscopic methods and via X-ray crystallographic determinations of two of its derivatives, the THF adduct (2) and the neutral chloride derivative 3 formed upon addition of Cl− to 1. Detailed mechanistic experiments suggest 1 is formed via insertion of neohexene into the Ti−Me bond of [Cp*Ti(NPtBu3)Me][B(C6F5)4] to give a detectable intermediate (4), which was characterized spectroscopically. Cation 4 reacts in a σ-bond metathesis reaction with the olefinic C−H bond trans to the tert-butyl group of another equivalent of neohexene to form an undetected cationic vinyl intermediate, which rapidly inserts a third equivalent of neohexene to generate 1. Deuterium labeli...

Rhodium-Complex-Catalyzed Addition Reactions of Chloroacetyl Chlorides to Alkynes

The addition reaction of chloroacetyl chloride derivatives with terminal alkynes was found to be catalyzed by Rh(acac)(CO)(AsPh(3)) to afford (Z)-1,4-dichloro-3-buten-2-one derivatives, which displayed diverse reactivities in synthetic elaboration.

Dapson in Heterocyclic Chemistry, Part IV: Synthesis of Some Novel Diphenylsulfones Containing Acetamide, Pyrrolidine, Piperazine, and Thiomorpholine Moieties as Antimicrobial and Antitumor Agents

Interaction of dapson [bis(4-aminophenyl)sulfone] 1 with [bis-(methylsulfonyl) methylidine]malononitrile 2 yielded the corresponding dicyano derivative 3, which was reacted with acetic anhydride, succinic anhydride, 4-chlorobenzaldehyde, phenyl isothiocyanate to give the corresponding acetamide 4, succinamic acid 5, pyrrolidine 6, Shiff base 7 and thiourea 8, respectively. Treatment of 3 with chloroacetyl chloride afforded the aminoacetyl chloride derivative 9. Further, the interaction of compound 9 with thioglycolic acid, malononitrile, ethyl glycinate hydrochloride, and/or potassium thiocyanate furnished compounds 10–15, respectively. The structural characterization of the prepared compounds was based on microanalytical and spectroscopic analyses. Some of the prepared compounds were tested for their antimicrobial and antitumor activities. Compounds 9 and 12 showed promising antitumor activity compared with Doxorubicin as positive control.

Mesoporous Molecular Sieve MCM‐41 as a Novel and Efficient Catalyst to Synthesis of 2‐Substituted Benzimidazoles

Abstracto‐Phenylenediamine derivatives readily react with benzoyl chloride derivatives in the presence of MCM‐41 as catalyst to yield 2‐substituted benzimidazoles in very good yields.

Use of C,N-chelated di-n-butyltin(IV) fluoride for the synthesis of acyl fluorides, fluoroformates and fluorophosgene

{2-[(CH3)2NCH2]C6H4}(n-Bu)2SnF (1) reacts with various chloroformates, acyl chlorides, methanesulfonyl chloride, 4,4′-dimethoxytrityl chloride and phosgene precursors or derivatives to form fluorinated analogues. All reactions proceed rapidly and under mild conditions. The use of a catalytic amount of 1 and KF in toluene led to a relatively high yield of a selected fluoroformate.

Copper(I) Diphosphine Catalysts for C−N Bond Formation: Synthesis, Structure, and Ligand Effects

A series of copper(I) complexes containing bis(diarylphosphino)propane, bis(diarylphosphino)ethane, bis(diarylphosphino)methane, and N,N-bis(diarylphosphino)amine ligands (Aryl = Ph, 2-C6H4(Me) or 2-C6H4(i-Pr)) has been synthesized. Crystal structures of selected chloride derivatives are reported. The complex structures proved to be very sensitive to both the backbone and P-substituents of the chelating ligand. The complexes have been screened for catalytic amidation reactions. Although in most cases only very low activity is observed, comparable with simple copper halide salts, notable exceptions are catalysts based on N,N-bis(diphenylphosphino)amine ligands, where a significant improvement in catalyst efficiency is observed. We propose the unusual electronic properties of these ligands may be the cause of their distinctive performance in these and other catalytic reactions where hard donor ligands have previously been employed.