Synthesis of dirhodium(II) tetrakis[methyl 1-(3-phenylpropanoyl)-2-oxaimidazolidine-4(S)-carboxylate], Rh2(4S-MPPIM)4

The large-scale synthesis with greatly improved yields of methyl 1-(3-phenylpropanoyl)-2-oxaimidazolidine-4(S)-carboxylate and the chiral dirhodium(II) carboxamidate derived from it, Rh₂(4S-MPPIM)₄, is described. The key step in the overall synthesis is the Hofmann rearrangement of Boc-protected l-asparagine, the procedure for which has been modified to achieve near quantitative yield.     

Convenient synthesis of N-(4-(2-aminopyridin-4-yl)thiazol-2-yl)-2-phenylacetamides

We report a facile one-pot, three-step synthesis of N-(4-(2-aminopyridin-4-yl)thiazol-2-yl)-2-phenylacetamides via condensation of 2-p-methoxybenzylamino-4-acetylpyridine with phenylacetylthioureas.     

Kinetic and thermodynamic study of the Na4(UO2)2(OH)4(C2O4)2 complex

The synthesis, the characterization, and the thermal decomposition of the dioxouranium(VI) ternary complex of formula Na₄(UO₂)₂(OH)₄(C₂O₄)₂, has been studied. The identification of the compound was performed by chemical analysis and by infrared spectrometry. Thermal decomposition of the compound occurs in several steps due to the decomposition of the salt to Na₂O and UO₃ oxides. The stoichiometry of the steps, hypothesized by means of the thermodynamic and kinetic parameters, is confirmed by the evolved gas analysis studied by FTIR spectrometer coupled to TG/DSC apparatus. Model‐fitting and model‐free kinetic methods have been used in kinetic analysis. The latter allows determining kinetic scheme. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 661–669, 2003     

SYNTHESIS AND STRUCTURE OF (Et_4N)_2[Ni_2(OSC_5H_4)_2(μ-SC_6H_4OH)_2]

<正> The synthesis and structure of cluster compound(Et4N)2[Ni2-(OSC6H4)2(u-SC6H4OH)2] are reported. Mr = 876.54,space group P21/n, a = 9.179(4), b = 17.487(6), c = 12.840(4) A;B=92.87(3)°;V=2058.6(2)A3; Z = 2; DC = 1.182g·cm-3.     

Synthesis of Pb8Pr2(GeO4)4(VO4)2 and refinement of its crystal structure

The conditions of synthesis of lead praseodymium vanadatogermanate Pb₈Pr₂(GeO₄)₄(VO₄)₂ with an apatite structure were determined by X-ray powder diffraction. The elemental composition and homogeneity of the synthesized sample were verified by scanning electron microscopy. The crystal structure was refined by the Rietveld method.     

Efficient and beta-Stereoselective Synthesis of 4(5)-(beta-D-Ribofuranosyl)- and 4(5)-(2-Deoxyribofuranosyl)imidazoles(1)

A synthetic route to 4(5)-(beta-D-ribofuranosyl)imidazole (1), starting from 2,3,5-tri-O-benzyl-D-ribose (5), was developed via a Mitsunobu cyclization. Reaction of 5 with the lithium salt of bis-protected imidazole afforded the corresponding 5-ribosylimidazole 7RS. Hydrolysis of 7RS gave a 1:1 mixture of diol isomers 8R and 8S having an unsubstituted imidazole. Mitsunobu cyclization of the mixture 8RS using N,N,N',N'-tetramethylazodicarboxamide and Bu(3)P exclusively afforded benzylated beta-ribofuranosyl imidazole 9beta in 92% yield, accompanied by alpha-anomer 9alpha, in a ratio of 26.3:1. The configuration of 9beta was established by X-ray crystallography of ethoxycarbonyl derivative 10beta. Reductive debenzylation of 9beta over Pd/C was carried out, and the synthesis of 1 was attained from starting 5 in four steps and 87% overall yield. This synthetic methodology was extended to the synthesis of 4(5)-(2-deoxy-beta-D-ribofuranosyl)imidazole (2). Mitsunobu cyclization of a 1:1 mixture of the corresponding diol isomers 14RS produced 15beta and 15alpha in a ratio of 5.4:1. The synthesis of 2 was attained in a 59% overall yield from the starting 3,5-di-O-benzyl-2-deoxy-D-ribose (12). beta-Stereoselective glycosylation in the key step is discussed and explained by intramolecular hydrogen bonding between an NH in the imidazole and the oxygen functional group in the sugar moiety.     

Synthesis and Crystal Structure of 4-Chloro-N- （2-（2-nitrophenyl）acetoxy）-N-（m-tolyl）benzamide

The new title compound 4-chloro-N-(2-(2-nitrophenyl)acetoxy)-N-(m-tolyl)benzamide(C22H17ClN2O5, Mr = 424.82) has been synthesized via the reaction of 4-chloro-N-hydroxy-N-(m-tolyl)benzamide with 2-(2-nitrophenyl)acetyl chloride. The structure of the product was confirmed by 1H NMR, 13 C NMR, IR, HRMS(ESI) and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/c with a = 13.0269(10), b = 6.7251(6), c = 23.9313(16) , β = 99.931(6)o, V = 2065.1(3) 3, Z = 4, Dc = 1.366 g/cm3, F(000) = 880, μ = 0.221 mm-1, the final R = 0.0600 and wR = 0.1754 for 1981 observed reflections(I 2σ(I)). X-ray analysis indicates that the chloro-phenyl ring(C(10)~C(15)) and the methyl-substituted benzene ring(C(16)~C(21)) are not coplanar with the nitro-substituted benzene ring(C(1)~C(6)), with the dihedral angle to be 70.78° and 63.72°, respectively. Hydrogen bonds C(2)–H(2)···O(2) and C(7)–H(7B)···O(5) are observed.     

2-(4-Tolylsulfonyl)ethoxymethyl (TEM)-a new 2'-OH protecting group for solid-supported RNA synthesis

The 2-(4-tolylsulfonyl)ethoxymethyl (TEM) as a new 2'-OH protecting group is reported for solid-supported RNA synthesis using phosphoramidite chemistry. The usefulness of the 2'-O-TEM group is exemplified by the synthesis of 12 different oligo-RNAs of various sizes (14-38 nucleotides long). The stepwise coupling yield varied from 97-99% with an optimized coupling time of 120 s. The synthesis of all four pure phosphoramidite building blocks is also described. Two new reliable parameters, delta(C2')-delta(C3') and delta(H2')-delta(H3'), have been suggested for the characterization of isomeric 2'-O-TEM and 3'-O-TEM as well as other isomeric mono 2'/3'-protected ribonucleoside derivatives. The most striking feature of this strategy is that the crude RNA prepared using our 2'-O-TEM strategy is sufficiently pure (>90%) for molecular biology research without any additional purification step, thereby making oligo-RNAs easily available at a relatively low cost, saving both time and lab resources.     

Pd-Cu-catalyzed synthesis of N-(2E,4)- and N-(2Z,4)-enyne cyclic amines

By Pd-Cu-catalyzed coupling of (2E)- and (2Z)-3-chloroprop-2-en-1-ylamines and alkynes a stereoselective method of the synthesis was developed for a series of (2E,4)- and (2Z,4)-enyne cyclic amines.     

Magneto-structural study and synthesis optimization of a phosphovanadate copper complex, [Cu(VO)2(PO4)2(H2O)4] n

The optimized synthesis of a phospho-vanadyl compound, [Cu(VO)₂(PO₄)₂(H₂O)₄] _n , is presented and its structural analysis is performed and discussed in relation to magnetic properties. The structure consists of a 2-D skeleton parallel to (100), made up by two independent VO₆ octahedra linked by phosphates. Neighboring 2-D structures stack along [100] and are connected by aqua-mediated H-bonds. The spatial disposition of paramagnetic ions gives rise to weak antiferromagnetic behavior, with J?=??17?cm^?1, which is consistent with a model of three paramagnetic centers in an irregular triangular arrangement. An optimization of the synthesis process, looking for a response surface with optimum experimental values, was performed using a multivariate analysis.     

4-(2-di-n-propylaminoethyl)-7-methoxyindole

Preparation of the title compound has been achieved by a modification of the Reissert indole synthesis, starting with 2-nitro-3-methyl-4-cyanoanisole ( 3 ), and homologation of the CN group of the resulting 4 -cyano-7-methoxyindole. The starting material 3 was prepared by bromination of 2-nitro-3-methylphenol, and the structure of the bromination product was verified chemically.     

Synthesis of Derivatives of (4-Methyl-2-Quinolylthio)acetic and (4-Methyl-2-Quinolylthio)propionic Acids

An efficient synthesis has been developed for derivatives of (4-methyl-2-quinolylthio)acetic and (4-methyl-2-quinolylthio)propionic acids by the reaction of 4-methyl-2-thioxoquinoline with methyl methacrylate, the amide of methacrylic acid, acrylonitrile, ethyl bromoacetate, and ethyl acrylate. The hydrolysis of the resultant intermediates by (quinolylthio)acetic and (quinolylthio)propionic acids gave the corresponding acid products, which are also formed in the reaction of 4-methyl-2-thioxoquinoline with chloroacetic and acrylic acids. The reaction of 4-methyl-2-thioxoquinoline with allyl bromide was studied. The potassium permanganate oxidation of the resultant 2-allylthio-4-methylquinoline led to (4-methyl-2-quinolylthio)acetic acid.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 403–406, April, 2005.     

Structure of the Cu(II) chloride complex with 4-amino-l,2,4-triazole Cu(C2H4N4)Cl2

The coordination compounds of copper(II) chloride and bromide with 1,2,4-triazole (L¹) and 4-amino1,2,4-triazole (L²), CuL¹Hal₂ and CuL²Hal₂, possess interesting magnetic properties [1, 2]. For example, at very low temperatures CuL¹Cl₂ and CuL¹Br₂ are ferromagnets [2](T _c ≈ 3.3 and 6.5 K, respectively). To explain the magnetic behavior of copper(II) halide complexes with the above nitrogen heterocycles it is generally assumed that the complexes are polynuclear chain compounds in which the copper atoms are bridged by two halogen ions and bridging bidentate heterocycle molecules (coordination of N1 and N2 atoms). This hypothesis is made on the basis of the X-ray diffraction analysis of CuL¹Cl₂ [3]. It is interesting to perform an X-ray diffraction study of CuL²Cl₂ and CuL2Br2; this is important for obtaining reliable magnetostructural correlations for this group of compounds. In this study, we investigated single crystals of the complexes; this demanded choosing special conditions of synthesis, which differ from the conditions suggested for the synthesis of polycrystals in [1]. In this communication we report on the results of synthesis and X-ray diffraction analysis of the single crystals of the coordination compound CuL²Cl₂. Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 1, pp. 207–212, January–February, 1997.     

A Practical Synthesis of 2-Butyl-4(5)-chloro-5(4)-hydroxymethyl- 1H-imidazole

A practical process for the synthesis of 2-butyl-4-hydroxymethyl imidazole (4) followed by chlorination to provide chloroimidazole 1 in an overall 71% yield has been developed.     

Highly efficient approach to orthogonally protected (2S,4R)- and (2S,4S)-4-hydroxyornithine

[reaction: see text] A concise stereoselective approach to both orthogonally protected (2S,4R)- and (2S,4S)-4-hydroxyornithine, key constituents of the biphenomycin- and clavalanine-type antibiotics, respectively, has been developed. The approach is based on bis(oxazoline) copper(II)-complex-catalyzed diastereoselective Henry reactions of nitromethane with the homoserine-derived aldehyde 6. The synthesis of this versatile chiral building block has been markedly improved.     

An improved synthesis of cis-4-phenyl-2-propionamidotetralin (4-P-PDOT): a selective MT(2) melatonin receptor antagonist

A novel, efficient and diastereoselective procedure was developed for the gram-scale synthesis of cis-4-phenyl-2-propionamidotetralin (4-P-PDOT), a selective MT(2) melatonin receptor antagonist. The synthetic strategy involved the conversion of 4-phenyl-2-tetralone to enamide followed by diastereoselective reduction affording cis-4-P-PDOT in good yield. The mechanism of the reduction step was explored by employing deuterated reagents.     

On the road to a termolecular complex with acetone: a heterometallic supramolecular network [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]

A novel heterometallic supramolecular network [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]](2)( infinity ) has been prepared by codeposition of the volatile mono(acetone) adduct [Rh(2)(O(2)CCF(3))(4).eta(1)-OCMe(2)](2) and copper(I) trifluoroacetate, [Cu(4)(O(2)CCF(3))(4)]. The product is of interest from the viewpoints of gas-phase supramolecular synthesis and a rare bridging coordination mode of acetone. It has been fully characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction. An X-ray structure revealed a layered 2D arrangement of the heterometallic [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]] units built by axial intermolecular interactions of the open electrophilic Rh(II) and Cu(I) centers and O-atoms of neighboring carboxylate groups. The coordination of the acetone molecules within the [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]] unit is asymmetric with the Rh-O and Cu-O distances being 2.2173(15) and 2.7197(17) A, respectively. This work shows the potential of gas-phase deposition that may provide additional possibilities in supramolecular synthesis by utilizing intermolecular interactions and coordination bonds in a new way compared with conventional solution chemistry.     

Titanium(II) and titanium(III) tetrahydroborates. Crystal structures of [Li(Et2O)2][Ti2(BH4)5(PMe2Ph)4], Ti(BH4)3(PMe2Ph)2, and Ti(BH4)3(PEt3)2

The molecular structures of the titanium(III) borohydride complexes Ti(BH4)3(PEt3)2 and Ti(BH4)3(PMe2Ph)2 have been determined. If the BH4 groups are considered to occupy one coordination site, both complexes adopt distorted trigonal bipyramidal structures with the phosphines in the axial sites; the P-Ti-P angles deviate significantly from linearity and are near 156 degrees. In both compounds, two of the three BH4 groups are bidentate and one is tridentate. The deduced structures differ from the one previously described for the PMe3 analogue Ti(BH4)3(PMe3)2, in which two of the tetrahydroborate groups were thought to be bound to the metal in an unusual "side-on" (eta(2)-B,H) fashion. Because the PMe3, PEt3, and PMe2Ph complexes have nearly identical IR spectra, they most likely have similar structures. The current evidence strongly suggests that the earlier crystal structure of Ti(BH4)3(PMe3)2 was incorrectly interpreted and that these complexes all adopt structures in which two of the BH4 groups are bidentate and one is tridentate. The synthesis of the titanium(III) complex Ti(BH4)3(PMe2Ph)2 affords small amounts of a second product: the titanium(II) complex [Li(Et2O)2][Ti2(BH4)5(PMe2Ph)4]. The [Ti2(BH4)5(PMe2Ph)4]- anion consists of two Ti(eta(2)-BH4)2(PMe2Ph)2 centers linked by a bridging eta(2),eta(2)-BH4 group that forms a Ti...(mu-B)...Ti angle of 169.9(3) degrees. Unlike the distorted trigonal bipyramidal geometries seen for the titanium(III) complexes, the metal centers in this titanium(II) species each adopt nearly ideal tbp geometries with P-Ti-P angles of 172-176 degrees. All three BH4 groups around each Ti atom are bidentate. One of the BH4 groups on each Ti center bridges between Ti and an ether-coordinated Li cation, again in an eta(2),eta(2) fashion. The relationships between the electronic structures and the molecular structures of all these titanium complexes are briefly discussed.     

Synthesis and Identification of 2-(4-hydroxyphenoxy) Propionic Acid

The synthesis of 2-(4-hydroxyphenoxy) propionic acid, useful as an important intermediate for herbicides, had been reported^[1-3]. In this paper, The synthesis of 2-(4-hydroxyphenoxy)propionic acid had been studied by the reacting hydroquinone with cheap 2-chloropropionic acid in the presence of base.     

2-Cyano-N-(4-sulfamoylphenyl) Acetamide as a Synthon in Heterocyclic Synthesis

This review describes the synthesis and reactions of 2-cyano-N-(4-sulfamoylphenyl) acetamide as a building block for the synthesis of polyfunctionalized heterocyclic compounds including its synthesis, reactivity, and reaction.