Syntheses and structural characterizations of Fe_4S_4 cubane-like cluster compounds containing cycloalkylthiolate ligands

In a reaction system consisting of FeCl2,tetrathiometallate and cycloalkylthiolate,two Fe4S4 cubane-like cluster compounds were obtained with the following crystallographic data:(PhCH2NMe32[Fe4S4 (SC5H9)4](Ⅰ),monoclinic space group P21/c,a=1.6327(4),6=1.1229(3),c=2.802 5( 10) nm,β=94.63(2)°,Z=4,and R=0.074; (Et4N)2[Fe4S4(SC6H11)4](Ⅱ),tetragonal space group I42m,a=1.16705(9),b=1.167 06(2),c=2.063 26(5) nm,Z=2,Dabs=1.28 g/cm3,and R=0.078 The participation of cy-cloalkylthiolate ligand does not obviously arouse the change of the Fe4S4 core structure.Meanwhile,the influence of the cation on the structural symmetry of the Fe4S4 cluster dianion is also discussed.     

Syntheses of Benzoxepinoquinolinone and Benzothiepinoquinolinone

l-Benzoxepino(3, 4-b)quinolin-l3(6H)-one and its halogen,alkyl, alkoxy derivatives Va'-d' and 1-benzothiepino(3,4-b}-quinolin- 13 ( 6H)-one Vf, and its alkyl derivatives Vg, weresynthesized through cyclization of 2-(substituted phenoxymethyl)-3-quinolinecarboxylic acids Va-d and 2-[ (un)substituted phen-ylthiomethyll-3-quinolinecarboxylic acids IVf-g in the presence ofpolyphosphoric acid.The acids IV were obtained from the corresponding ethyl-esters @ whcih were prepared through refluxing ethyl 2-bromo-methyl-3-quinolinecarboxylate(1) with substituted phenol or (un)substituted thiophenol in the presence of NaOEt.The compound Vg, was allowed to react with NBS, KaBH4, NH2OH-HCl to give compounds VII , VIII, and IX, respectively.The structures of 24 new compounds have been confirmed by elemental analysis, IR and 1H NMR.     

Syntheses,characterizations and SOD-like activities of ternary copper(II) complexes with 1,10-phenanthroline and L- α -amino acids

Three new complexes, [Cu(phen)(L-argH⁺)Cl]Cl?·?2.5H₂O (1), [Cu(phen)(L-leu)(H₂O)]Cl?·2.5H₂O (2) and [Cu(phen)(L-met)(H₂O)]Cl?·?2H₂O (3), where phen?=?1,10-phenanthroline, L-arg?=?L-argininate, L-leu?=?L-leucinate, and L-met?=?L-methioninate, were synthesized and characterized by elemental analysis, molar conductivity, IR and UV-Vis spectroscopies. Complex 1 was structurally characterized by single-crystal X-ray diffraction. The superoxide dismutase (SOD)-like activities of the three complexes were determined by the improved NBT method. The results show that the complexes have high superoxide dismutase-like activities and may act as good mimics for superoxide dismutases.     

The asymmetric synthesis of chiral cyclic α-hydroxy phosphonates and quaternary cyclic α-hydroxy phosphonates

A highly practical, catalytic enantioselective cyclic phosphite addition to aldehydes and ketones was developed. The reaction rate of the asymmetric hydrophosphonylation was significantly enhanced by the addition of silver carbonate. Particularly, significant improvement has been achieved on the asymmetric hydrophosphonylation of unactivated ketones, giving quaternary α-hydroxy phosphonates with excellent enantioselectivity (up to 99% ee).     

Syntheses and Studies of PEG-b-PNIPA Block Polymers

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Total Syntheses of Aurachins A and B

Aurachins A and B are alkaloids having 3-hydroxyquinoline N-oxide cores. An efficient method for the synthesis of 3-hydroxyquinoline N-oxides was established and is amenable to the total syntheses of aurachins A and B. Alkylation of 1-(2-nitrophenyl)butan-2-one with farnesyl bromide took place selectively at the benzylic position, and subsequent treatment of the alkylated product with sodium tert-butoxide in dimethyl sulfoxide gave aurachin B. Alkylation of 1-(2-nitrophenyl)butan-2-one with an epoxy iodide derived from farnesol was used to access aurachin A.     

Syntheses and characterization of the noble-metal substituted heptadecatungstodiarsenates

Four Dawson type heteropolyoxotungstates substituted by noble metals with the general formula (TBA)n[As2W17M(OH2)O61], where M=PdII, RuIII, IrIV and PtIV, are prepared by filling the vacant site of the lacunary precursor a2-K10As2W17O61. UV-vis and IR spectra are similar to the other transition metal substituted Dawson type tungstodiarsenates. EPR result provides direct evidence to identify the presence of noble metal cation. Electrochemical behavior investigated by cyclic voltammetry in acetonitrile displays four reversible one-electron redox couples attributed to the W(VI-V) process of tungsten-oxo framework.     

Synthesis of ��-hydrazino phosphonates from l-amino acid- and l-glutathione-derived hydrazones

[Tetra(tert-butyl)phthalocyanine]aluminum chloride catalyzed hydrophosphorylation of cyclic ketone hydrazones, which were derived from hydrazides of l-amino acids and glutathione, resulted in polyfunctional ??-hydrazino phosphonates.     

Syntheses and Properties of Tripicolinatechromium (Ⅲ)

Chromium (Ⅲ) has been implicated as glucose tolerance factor (GTF) in the maintenance of normal lipid and carbohydrate metabolism^[1]. Several organic chromium (Ⅲ) complexes containing nicotinate, amino acids ligand which have much higher biological activity than chromic chloride have been synthesized and extensively studied^[2]. Tripicolinatechromium (Ⅲ) as a new human chromium(Ⅲ) nutritional supplement was shown to reduce the symptoms of diabetes, hyperglycemia and cholesterol significantly^[3]. Although the crystal structure and NMR spectrum of tripicolinatechromium (Ⅲ) was studied previously^[4,5], Its properties have only received little attention. In this paper, we report the studies of syntheses and properties of tripicolinatechromium(Ⅲ).     

Syntheses and transformations of α-azido ketones and related derivatives

Organic azides are known and utilized in the synthetic organic chemistry as amine precursors, potential sources of nitrenes, dipoles useful in 1,3-dipolar cycloadditions and starting materials of phosphoranes for a long time, and their literature has been overviewed by several authors. On the other hand, there are some special subclasses within the azides which possess peculiar and interesting properties differing from those of the majority and offering extra synthetic possibilities. In this critical review we wish to give an exhaustive overview on the synthesis and synthetic potential of α-azido ketones and related systems, an underestimated group of compounds. The enhanced acidity of the α-hydrogen offers various new synthetic applications including the creation of a new C-C bond, while the joint presence of the carbonyl and vinyl functions of α-azido-α,β-unsaturated ketones results in a special reactivity, too. Chemo- and stereoselectivity issues also represent important points which are discussed in detail. Finally, the usefulness of the titled derivatives in the synthesis of various heterocycles is reviewed (273 references).     

Syntheses and Structures of Sil abridged Hafnocene Dichlorides

The present paper covers three silabridged hafnocene dichlorides(1, 2 and 3) prepared by sequential reactions of α, ω-dichloropermethyl polysilane with cyclopentadienyl sodium, n-butyl lithium and hafnium tetrachloride. Their structures were characterized by elemental analyses, UV, 1H(13C) NMR and MS. Furthermore the crystal and molecular structures of 1 and 2 were determined by X-ray diffraction method. The crystal of 1 is monoclinic, space group C2/c with a=1. 3401(4), b=0. 9977(3), c = 1. 0922(4) nm; β=94. 07(1)° V=3. 6342 nm3, Z = 2, Dc = 2.155 g·cm-3. The final deviation factor R = 0. 064. The crystal of 2 is monoclinic, space group P21/c with a=0.0847(1), b=1.5181(1), c=2.9824(2) nm; β= 94. 07(1)°? V=3.634 nm3; Dc= l. 805 g·cm-3. The final deviation factor R = 0. 033. The relationship between the silabridged structure and spectral properties is also discussed.     

Syntheses and Structure-Odor Relationship of Some γ-Lactones

A lot of norbornene derivatives and lactones are widely used as fragrant components in food or cosmetics. We expected that a series of new compounds with better odor character could be obtained when these two skeleton structures were combined. Thus, a series of endoand exo-5,5-disubstituted-3-oxo-4-oxatricyclo[5,2,1,0~(2,6)]dec-8-enes(Ⅰ) were synthesized.     

Syntheses and Photo-electronic Properties of Lanthanide Acetylacetonate Benzoporphyrins

Metalloporphyrin compounds have been extensively studied in many functional chemistry fields, such as photo-physics and liquid crystal quality studies^[1-5]. But the studies of lanthanide acetylacetonate benzoporphyrin complexes with meso-tetra-alkyl substituents in the ligand [Ln(TATBP)acac] have not been reported yet.     

Reactions of acyl phosphonates with organoaluminum reagents: a new method for the synthesis of secondary and tertiary α-hydroxy phosphonates

The reactions of organoaluminum reagents (trimethylaluminum, triethylaluminum, etc.) with aryl and alkyl acyl phosphonates, which lead to the formation of α-hydroxy phosphonates in moderate to good yields, are reported. This method provides easy access to secondary and tertiary α-hydroxy phosphonates depending on the reaction conditions. The reactions of triethylaluminum with a series of acyl phosphonates at 0 °C gave the secondary α-hydroxy phosphonates, while at −100 °C they afford the tertiary α-hydroxy phosphonates.     

Synthesis and study of cesium-containing phosphates with a β-tridymite structure

Complex phosphates CsMg_{1 ? x} M _x PO₄ (M = Mn, Co, Cu, Zn), containing cesium and metals in the oxidation state +2, have been synthesized, and their structure and thermal behavior have been studied. Continuous solid solutions (0 ?? x ?? 1) of the ??-tridymite structure type are formed in the CsMg_{1 ? x} Mn _x PO₄, CsMg_{1 ? x} Co _x PO₄, and CsMg_{1 ? x} Zn _x PO₄ systems, whereas limited solid solutions (0 ?? x ?? 0.4) are formed in the CsMg_{1 ? x} Cu _x PO₄ system. Based on DTA data, phase transitions have been revealed in the cobalt-, copper-, and zinc-containing phosphates, and the orthorhombic or monoclinic crystal system has been identified. Unit cell parameters of the solid solutions have been calculated. Thermal expansion of the CsMPO₄ phosphates has been studied.     

Reaction of zirconocene dichloride with alkyllithiums or alkyl grignard reagents as a convenient method for generating a “zirconocene” equivalant and its use in zirconium-promoted cyclization of alkenes,alkynes, dienes,enynes, and diynes

Treatment of Cl₂ZrCp₂ with 2 equiv of alkylmetals (RM) containing Li or Mg, e.g., n-BuLi, in THF produces organozirconium species that act as sources of “ZrCp₂,” the latter product being a convenient reagent for preparing zirconacycles.     

Syntheses and applications of enantiopure δ-amino acids and their precursors

Enantiopure unnatural homologated amino acids, whereby there is?>?1 carbon atom between the C- and N- termini have found great utility in a number of applications. The enantiopure syntheses of β-amino acids are well documented, as increasingly are those of γ-amino acids. δ-Amino acids on the other hand are much less well-studied despite reports of their potential utility. This review attempts to summarise strategies that have been adopted towards the enantioselective synthesis of δ-amino acids and their precursors (e.g. nitrile/nitro/azido/ester/alcohol etc) and where appropriate demonstrate their utility. Only systems which are all carbon between the two termini are considered and only those where the shortest route between any given C-termini and any given N-termini is four carbons long (i.e. lysine derivatives are not considered).