Palladium(II)-catalyzed ring expansion of a 1-alkenyl cyclopentanol

7,7-Dimethyl-2-methylenenorbornan-1-ol, a strained bicyclic 1-alkenyl cyclopentanol, undergoes Wagner-Meerwein rearrangement to fenchone under treatment with a catalytic amount of PdCl₂(PPh₃)₂ in refluxing N-methylpyrrolidin-2-one. The described reaction constitutes the first example of the palladium(II)-catalyzed ring expansion of 1-alkenyl cyclopentanols to the corresponding cyclohexanones.     

A novel synthesis of (Z)-2-(1-trimethylgermyl-1-alkenyl)-1,3,2-dioxaborinanes and their conversion into carboxylic acids

A novel procedure for preparing heterocyclic compounds such as (Z)-2-(1-trimethylgermyl-1-alkenyl)-1,3,2-dioxaborinanes based on 1-trimethylgermyl-1-alkynes is described. 1-Trimethylgermyl-1-alkynes easily obtainable by deprotonation of 1-alkynes with n-butyllithium followed by treatment with trimethylgermanium chloride, are readily hydroborated in n-pentane in the presence of boron trichloride in hexane at 0 °C for 3 h. The resulting supernatant clear solution was separated from boron trichloride-methyl sulfide complex. It was then reacted with 1,3-propane diol at 0 °C for 0.5 h. The resulting representative (Z)-2-(1-trimethylgermyl-1-alkenyl)-1,3,2-dioxaborinanes were isolated in good yields (65-86%) and in high stereochemical purities (>98%) as evidenced by NMR spectral data. The carbon skeletons present in these intermediates were confirmed by alkaline hydrogen peroxide oxidation to the corresponding carboxylic acids.     

Regiochemistry of Palladium(II)-assisted oxidative lactonisation reactions.

The Pd(II)-assisted lactonisation of alkenoic acids has been studied. The selectivity, persisting to formation of 5- and 6-membered unsaturated lactones, can be governed by the change of solvent and/or base.     

Palladium(II) and platinum(II) 2-(methoxycarbonyl)ethylselenolates: Synthesis, spectroscopy, structures and their conversion into metal selenide

A diselenide, (MeOOCCH₂CH₂Se)₂ (1) has been prepared by esterification of (HOOCCH₂CH₂Se)₂ in methanol. The reductive cleavage of Se-Se bond in 1 by NaBH₄ in methanol generates MeOOCCH₂CH₂SeNa. The latter in different stoichiometries reacts with [M₂Cl₂(μ-Cl)₂(PR₃)₂] to give a variety of products of compositions [M₂Cl₂(μ-SeCH₂CH₂COOMe)₂(PR₃)₂] (2); [M₂Cl₂(μ-Cl)(μ-SeCH₂CH₂COOMe)(PR₃)₂] (3); [Pd₂(SeCH₂CH₂COOMe)₂(μ-SeCH₂CH₂COOMe)₂(PR₃)₂] (4);[Pd₃Cl₂(μ-SeCH₂CH₂COOMe)₄(PR₃)₂] (5). Treatment of complexes 2 with [M₂Cl₂(μ-Cl)₂(PR₃)₂] affords complexes 3 in nearly quantitative yield. The formation of various products in these reactions is sensitive to stoichiometric ratio of reactants employed. This enables interconversion of various complexes by manipulating mole ratios of appropriate starting materials. A homoleptic palladium complex, [Pd(SeCH₂CH₂COOMe)₂]₆ (6) was isolated from a reaction between Na₂PdCl₄ and MeOOCCH₂CH₂SeNa. All these complexes have been characterized by elemental analysis, IR, UV-Vis and NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹⁹⁵Pt) spectroscopy. Structures of trans-[Pd₂Cl₂(μ-SeCH₂CH₂COOMe)₂(PPh₃)₂] (2d), [Pt₂Cl₂(μ-Cl)(μ-SeCH₂CH₂COOMe)(PⁿPr₃)₂] (3e), [Pd₃Cl₂(μ-SeCH₂CH₂COOMe)₄(PⁿPr₃)₂] (5) and [Pd(SeCH₂CH₂COOMe)₂]₆ (6) have been established unambiguously by X-ray crystallography. In these complexes, there are bridging selenolate ligands with their uncoordinated ester groups. Compound 6 has a centrosymmetric Pd₆Se₁₂ hexagon in which every two palladium atoms are bridged by selenolate ligands. Thermal behaviour of some complexes has been investigated. Pyrolysis of compound 2b in tributylphosphate at 195 °C gave Pd₁₇Se₁₅ nanoparticles which were characterized by XRD and EDAX.     

S-烃基-1-烃基-3-[4-(5-取代苯并咪唑-2-巯基)苯基]异硫脲的合成及生物活性

以 5 甲氧基 (或氯 ) 2 巯基苯并咪唑 ( 1)为原料 ,经缩合和还原得到 5 甲氧基 (或氯 ) 2 ( 4 氨基苯硫基 )苯并咪唑 ( 3 ) ,再与异硫氰酸烃基酯反应得到取代硫脲 4,最后与卤代烃反应得到 12个新的S 烃基 1 烃基 3 [4 ( 5 甲氧基 (或氯 )苯并咪唑 2 巯基 )苯基 ]异硫脲化合物 5 .其结构经IR ,1 HNMR ,MS及元素分析确证 .初步的药理试验表明 ,12个目标化合物的iNOS抑制活性均强于阳性对照药氨基胍     

Molecular and Crystal Structure of 1- ( 2- chloro) - Benzoyl - 3- (4- methylphenyl ) Thiourea

1　INTRODUCTIONBenzoylphenyltioureas having a generalformula( ) were reported to have in secticidalactivity〔1〕,which isclosely related to theirstructures,particularly tothedi hedralangle between the- CONH- plane and phenylring〔2〕.Surprisingly there islittle reported in the literature,only three related structures stored in CSD〔3〕 until1 998.In thispaper,we reportthe crystalstructure ofthe title compound.R CONHCSNHR2　EXPERIMENTAL2 .1　Synthesis　　The synthesisofthetitl…     

Palladium(II) complexes with 1-allyl-3-(2-pyridyl)thiourea: Synthesis and spectroscopic characterization

New Pd(II) complexes with 1-allyl-3-(2-pyridyl)thiourea (APTU) of the formulas [Pd(C₉H₁₁N₃S)Cl₂] (I) and [Pd(C₉H₁₁N₃S)₂]Cl₂ (II) were obtained and examined by UV-Vis, IR, and 1H NMR spectroscopy. The conditions for the complexation reactions were optimized. The instability constants and molar absorption coefficients of these complexes were calculated. Comparison of the characteristic bands in the UV-Vis and IR spectra of the complexes and free APTU revealed that the ligand in both complexes is coordinated to the metal atom in the thione form in the bidentate chelating mode through the S atom of the thiourea group and the pyridine N atom. In the UV-Vis spectra of the complexes, the charge transfer bands (π → π* Py) and n → π* (C=N_Py), (C=S) experience hypsochromic shifts by 450–470 cm⁻¹ caused by the coordination of APTU to the metal ion, which gives rise to ligand-metal charge-transfer bands (C=N_Py → Pd, n → π* (C=S)) and (SPd). The protons in the 6-, 4-, and 3-positions of the pyridine ring and the thiourea NH proton in the chelate ring are most sensitive to the complexation.     

Spectrophotometric Determination of Palladium(II) with n-Hydroxy-N,N-Diphenylbenzamidine and 1 -(2-Pyridylazo)-2-Naphthol

A spectrophotometric method to determine palladium(II) at trace levels is based on the extraction of palladium(II) as a binary complex with N-hydroxy-N,N′-diphenylbenzamidine (HDPBA) in chloroform at pH 5.0 ± 0.2. The complex shows maximum absorbance at 400 nm with molar absorptivity 6.4 × 10³ L mol^?1 cm^?1. The sensitivity of the Pd(II)-HDPBA complex was enhanced by the addition of l-(2-pyridylazo)-2-naphthol (PAN). The green coloured complex shows maximum absorbance at 620 nm with molar absorptivity 1.58 × 10⁴ L mol^?1 cm^?1. Sandell's sensitivity and the detection limit of the method are 0.0067 μg cm^?2and 0.1 μg Pd(II) mL^?1, respectively. Most common metal ions associated with palladium metal do not interfere. The effects of various analytical parameters on the extraction of the metal are discussed.     

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

Abstract

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml^?1) and palladium(II) (0.08 - 1.8 μg ml^?1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.     

Synthesis of 4-(1-alkenyl)isoquinolines by palladium(II)-catalyzed cyclization/olefination

A variety of 4-(1-alkenyl)-3-arylisoquinolines have been prepared in moderate to excellent yields by the Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes. The introduction of an o-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Ketone-containing isoquinolines 36 and 49-51 have also been prepared by this process when unsaturated alcohols are employed as the alkenes.     

Palladium(II)-assisted ortho alkylation of C(sp2)-H bonds in substituted azobenzenes with simple alkyl halides

Abstract

A new and relatively simple synthetic strategy has been described for Pd(II)-catalyzed C-C bond formation via alkylation of ortho C(sp²)-H bonds in substituted azobenzenes possessing (2-phenylamino)phenylazo directing group employing different alkyl iodides. The yields of various ortho alkylated products are found to be good to excellent (65%–85%). A palladocyclic intermediate complex has been isolated and fully characterized. Based on the experimental results and the isolation of the palladocyclic intermediate, a catalytic cycle involving a sequential C-H activation/oxidative addition followed by reductive elimination pathway has been proposed.     

Stereoselective synthesis of (Z)-2-fluoro-1-alkenyl(phenyl)iodonium tetrafluoroborates

[reaction: see text] (Z)-2-Fluoro-1-alkenyl(phenyl)iodonium salts were stereoselectively prepared by the reaction of alkynyl(phenyl)iodonium salts with aqueous HF in good yields. The method is applicable to the synthesis of fluoroalkenyliodonium salts having functional groups such as ketone, ester, and chloride. (Z)-2-Fluoro-1-alkene, (Z)-2-fluoro-2-alkenoate, and (Z)-beta-fluoroenyne could be stereoselectively prepared from the fluoroalkenyliodonium salt.     

Highly unusual conversion of 1-alkyl-2-(bromomethyl)aziridines into 1-alkyl-2-(N-alkyl-N-ethylaminomethyl)aziridines using methyllithium

1-alkyl-2-(bromomethyl)aziridines were transformed into 1-alkyl-2-(N-alkyl-N-ethylaminomethyl)aziridines upon treatment with 2-3 equiv. of methyllithium in THF or Et(2)O; the peculiarity in this transformation comprises the presence of an N-ethyl group in the end-products as well as the total number of carbon atoms, resulting from a highly unusual reaction course with a novel S(N)2'-type substitution at the aziridine moiety and liberation of acetylene from an intermediate vinylamine as the key reaction steps.     

On the Mechanism of Intramolecular Cyclization of Dialkyl(2-propynyl)[3-alkenyl(or aryl)-2-propynyl]-ammonium Salts

Given are experimental data indicating that base-catalyzed intramolecular cyclization of ammonium salts containing a 2-propynyl-like group together with a 3-alkenyl- or 3-aryl-2-propynyl group follows a concerted mechanism involving the 3-alkenyl- or 3-aryl-2-propynyl moiety as π⁴-fragment.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 369–371.Original Russian Text Copyright © 2005 by E. Chukhadzhyan, Gevorkyan, El. Chukhadzhyan, Kinoyan.     

Direct Conversion of 3-(2-Nitroethyl)-1H-Indoles into 2-(1H-Indol-2-yl)Acetonitriles

The recently discovered [4+1]-spirocyclization of nitroalkenes to indoles provided a convenient new approach to 2-(1H-indol-2-yl)acetonitriles. However, this reaction was complicated by the formation of inert 3-(2-nitroethyl)-1H-indole byproducts. Herein, we offer a workaround this problem that allows for effective transformation of the unwanted byproducts into acetonitrile target molecules.     

Palladium(II) Complexes of 1-vinylimidazole

Two new co-ordination compounds of Pd^II with 1-vinylimidazole of the formulae [PdL₄]Cl₂·3H₂O and trans-[PdL₂Cl₂], where L is a 1-vinylimidazole molecule, have been obtained. The compounds were characterised by spectroscopic, molar conductivity, thermogravimetric and magnetochemical measurements. Single crystal X-ray structure analyses of the complexes were also carried out. The compounds are diamagnetic with square-planar coordinatination around the palladium(II) ions. Other physico-chemical properties of the both complexes are compatible with their structures.     

Solid Phase Luminescence and Thermal Transformations of Palladium(II) Complexes with 3-(2-Pyridyl)-1,2,4-Triazoles

Theoretical and Experimental Chemistry - The thermal behavior and luminescent properties of palladium(II) Pd(LR)2 complexes with 3-(2-pyridyl)-5-R-1,2,4-triazoles (LR , where R = H, Ph, Me) in...