LD3- and λ5-1,3-Diphosphacyclobutadienes by Dimerisation of λ3- and λ5-Phospha-alkynes

Abstract

λ³-Phosphaalkynes 1 dimerize in the presence of cyclopentadienylcobaltbis (ethylene) (2) to yield λ³-1,3-diphosphacyclobutadienes, which are stabilized by complex formation (3). An excess of 2, finally, is responsible for the formation of the complex 4.     

Crystal structures of α- and β-EuPrCuS3

The crystal structure of the EuPrCuS₃ complex sulfide synthesized for the first time has been solved by X-ray powder diffraction. Crystals are orthorhombic, space group Pnma. EuPrCuS₃ has two polymorphs: the high-temperature phase of Ba₂MnS₃ structural type with unit cell parameters a = 8.0786(1) Å, b = 4.0288(1) Å, and c = 15.8389(2) Å and the low-temperature phase of BaLaCuS₃-isostructural with unit cell parameters a = 11.0819(2) Å, b = 4.0710(1) Å, and c = 11.4459(3) Å.     

Vibrational spectrum of α- and δ-TiCl3

The vibrational spectrum of α-TiCl₃ is assigned on the basis of a normal coordinate analysis. The i.r. bands shift to higher frequency from α- to δ-TiCl₃. This is discussed in terms of a dispersion relation for k_c in α-TiCl₃ and force constants, where the former is carried out for examining effect on disorder to the c axis in δ-TiCl₃. The shift is explained in terms of a change in force constants rather than disorder.     

Synthesis and reactivity of 3-(trichlorogermyl)propanoic acid and 3-(triphenylgermyl) propanoic acid

3-(Trichlorogermyl)propanoic acid (la) reacts with phenylmagnesium bromide in malar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a).In the compounds la and 2a theβ-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide.The compound la reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give l,l-diphenyl-3-(triphenylgermyl)propanol (4a).The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also.Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy.Moreover,the compound la reacted with phenylmagnsium bromide in molar ratio 1:6,then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3-(triphenylgermyl)-1-propene (5a) in one pot reaction.Alkyl Ge-C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride ( LiAlH4) in good yiel     

Synthesis and Crystal Structure of 3-（Trichloroacetyl） Indole

1 INTRODUCTION Indole and its derivatives have attracted much at-tention due to their chemical properties as well asbiological activities[1, . They have been widely used 2]as the materials for producing pigment, perfume,plant growth regulators, etc. Recently, it has alsobeen found that some indole derivatives present anti-tumor and antiviral activities[3～5]. During our sear-ches for bioactive compounds, a series of indole deri-vatives were synthesized, among …     

Characterization and crystal structures of solvated N′-(4-hydroxy-3-nitrobenzylidene)-3-methylbenzohydrazide and N′-(4-dimethyl-aminobenzylidene)-3-methylbenzohydrazide

Two new solvated benzohydrazone derivatives N′-(4-hydroxy-3-nitrobenzylidene)-3-methylbenzohydrazide-methanol-water (2/1/1) 2(C₁₅H₁₃N₃O₄)·CH₃OH·H₂O (1) and N′-(4-dimethylamino-benzylidene)-3-methylbenzohydrazide methanol monosolvate C₁₇H₁₉N₃O·CH₃OH (2) are prepared and characterized by elemental analysis, ¹H and ¹³C NMR, and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/c with unit cell dimensions a = 17.084(2) Å, b = 12.706(1) Å, c = 15.412(1) Å, β = 113.207(1)°, V = 3074.1(4) ų, Z = 4, R ₁ = 0.0567, and wR ₂ = 0.1209. Compound 2 crystallizes in the monoclinic space group P2₁/n with unit cell dimensions a = 15.058(1) Å, b = 6.658(1) Å, c = 17.211(2) Å, β = 94.189(2)°, V = 1720.8(3) ų, Z = 4, R ₁ = 0.0611, and wR ₂ = 0.1594. X-ray diffraction indicates that the asymmetric unit of 1 contains two independent benzohydrazone molecules, one methanol and one water molecules. The asymmetric unit of 2 contains one benzohydrazone molecule and one methanol molecule. Benzohydrazone molecules of the compounds display trans configurations with respect to the C=N double bonds. The crystal structures of the compounds are stabilized by hydrogen bonds and weak π...π interactions.     

Synthesis and Crystal Structure of 3-（4-Bromobenzyloxy）-6-morpholinopyridazine

The title compound 3-(4-bromobenzyloxy)-6-morpholinopyridazine(C15H16BrN3O2) was synthesized,and its crystal structure was studied.It crystallizes in the triclinic system,space group P with a = 8.3408(17),b = 8.8620(18),c = 10.832(2) ,α = 108.09(3),β = 91.28(3),γ = 100.90(3)°,Dc = 1.562 g/cm3,Z = 2,λ = 0.71073 ,μ(MoKα) = 2.769 mm-1,Mr = 350.22,V = 744.5(3) 3,F(000) = 356,the final R = 0.0522 and wR = 0.1366 for 2016 observed reflections with I > 2σ(I).In the crystal structure,the morpholine ring adopts a chair conformation with O(2) and N(3) atoms at the flap positions-0.656(7) and 0.622(6)  out of the mean plane formed by the other four C atoms,respectively.These molecules generate centro-symmetric dimers through intermolecular π-π interaction.     

Synthesis and Biological Properties of 3-(Dihydroxybenzoyloxy)methyl- and 3-(Diacetoxybenzoyloxy)methyl-7α-chlorocephalosporanate Sulfones

We describe the synthesis of tert-butyl esters of 3-(2-hydroxybenzoyloxy)methyl-, 3-(dihydroxybenzoyloxy)methyl-, and 3-(diacetoxybenzoyloxy)methyl-7-chlorocephalosporanic acid sulfones by reaction of tert-butyl ester of 3-bromomethyl-7-chlorocephalosporanic acid sulfone with salts of hydroxy- and acetoxy-substituted benzoic acids. We have investigated the elastase-inhibiting properties of the compounds obtained and also their in vitro cytotoxic activity.     

Chemistry and Application of Phosphonium and Arsonium Ylide(ⅩⅧ)——Stereoselective Syntheses of (Z)-3-Perfluoroalkyl--4-(3-Carboethoxy-2-f uranyl )-3-Butenoates

The stereoselective syntheses of (Z)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c were investigated. The reaction of (3-carboethoxy-2-fu-ranyl)-methyltriphenylphosphonium bromide 1 with methyl 2-perfluoroalkynoates 2a-c in the presence of K2CO3 at room temperature gives two adducts, (E)-methyl 3-per-fluoroalkyl-4-( 3-carboethoxy-2-furanyl )-2-triphenylphosphoranylidene-3-butenoates 3a-c and (E)-methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-4-triphenylphos-phoranylidene-2-butenoates 4a-c. (Z)-Methyl 3-perfluoroalkyl-4-(3-carboethoxy-2-furanyl)-3-butenoates 5a-c can be synthesized stereoselectively with high yields when an aqueous DMF solution of 3c, 4c or a mixture of 3a-b and 4a-b was heated at 140℃ for 8 h.     

Synthesis and structural characterization of camphanates of (−)-(2S3S,3S) and (+)-(2S,3R)-4-Phenyl-3-bromo-2-butanol diastereoisomers

The X-ray crystal structures of (–)-syn-4-phenyl-3-bromo-2-butyl camphanate (I) and (+-anti-4-phenyl-3-bromo-2-butyl camphanate (II) have been determined. Thesyn diastereoisomer of bromohydrin has the (2S,3S) absolute configuration whereas theanti diastereoisomer has the (2S,3R) absolute configuration. The crystallized derivatives I and II have been obtained by the reaction of each stereoisomer of bromohydrin, synthesized by reduction with baker's yeast, with (1S)-camphanic chloride. Crystal data: (I) C₂₀H₂₅BrO₄:M _w: 409.32; orthorhombic,P2₁2₁2₁;a=11.245(3),b=12.086(1),c=14.512(4) å; Z=4; finalR=0.053 for 1819 observed reflections. (II) C₂₀H₂₅BrO₄;M _w=409.32; monoclinic, P2₁;a=11.352(1),b=6.378(1),c=14.255(2) å,=110.38(1);Z=2; finalR=0.045 for 1672 observed reflections.     

The Synthesis and Reactivity of New μ 2- and μ 3-Aminophosphinidene Cobalt Complexes

The reaction of K[Co(CO)₄] and PCl₂(TMP) at –5°C leads to the unstable and reactive -phosphinidene complex [Co₂(CO)₆{-P(TMP)}] (1), while the same reaction carried out at 35°C gives the chlorophosphido and phosphinidene bridged cluster [Co₃(CO)₇{-P(Cl)TMP}{ ₃-P(TMP)}] (2) (TMP=2,2,6,6-tetramethylpiperidyl). Compound 1 reacts with dppm (dppm=bis(diphenyl- phosphino)methane) and [Co₂(CO)₈] to form the more stable substitution product [Co₂(CO)₄{-P(TMP)}(-dppm)] (3) and [Co₄(CO)₇(-CO)₃{ ₃-P(TMP)}] (4) respectively. The first example of a cationic ₃-phosphinidene cluster compound [Co₃(CO)₉{ ₃-P(TMP)}][AlCl₄] (5) is obtained from reaction of 3 with AlCl₃. The X-ray structures of clusters 2 and 5 are discussed.     

Synthesis and photochromism of dimers of 4,5- diaryl-2-(2,5-dimethylthiophen-3-yl)imidazolyl

4,5-Diphenyl, 4,5-di(4-methylphenyl), 4,5-di(4-methoxyphenyl)-2-(2,5-dimethylthioph-en-3-yl)imidazoles were synthesized. Oxidation of the obtained imidazoles with potassium ferricyanide in water-alcohol solution of alkali gave the corresponding dimers. The structures were characterized by IR, 1H NMR, mass spectroscopy and elemental analysis. The dimers showed photochromism in solution on irradiation.     

Structure and Transesterification Reaction of Methyl 3-（Phenyldihalostannyl）propionates

The title compounds, PhX2SnCHECHECO2Me （X = C1, 1a; Br, 1b; I, 1c）, readily underwent transesterification into the corresponding analogues, PhX2SnCH2CH2CO2R when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of the novel transesterification was suggested.     

Facile synthesis of Fmoc-protected phosphonate pSer mimetic and its application in assembling a substrate peptide of 14-3-3 ζ

Phosphatase-inert peptidomimetics containing phosphonate pSer analogue have been developed as valuable biological tools for probing and regulating pSer-dependent protein-protein interactions (PPIs) in cellular context. Herein, we report a facile and efficient synthesis route of Fmoc-protected phosphonate pSer mimetic and also present the application of this building block in the solid-phase synthesis of a phosphatase-resistant substrate peptide of 14-3-3 ζ, retaining 14-3-3 ζ binding efficacy similar to the parent pSer-containing peptide.     

Synthesis of α-CF3- and α-CCl3 substituted nitrogen heterocycles by aza Diels-Alder and cyclocondensation reactions

Convenient synthetic approaches for α-CF₃- and α-CCl₃ substituted pyridines, hydrogenated pyridines, azanorbornenes, 4H-1,2,4-thiadiazine- and 2H-1,2,6-thiadiazine-1,1-dioxides were developed on the basis of cycloaddition and cyclocondensation reactions of trihaloethaneimines and imidoyl chlorides.     

Synthesis and Crystal Structure of 9-[3-Oxo-1-（4-bromopheny）-3-phenypropyl] fluorine

A novel compound of 9-[3-oxo-1-(4-bromopheny)-3-phenypropyl]fluorine (3) was synthesized via nucleophilic addition reaction under solvent-free condition. Its structure was determined by IR, 1H NMR, MS, elemental analysis and X-ray diffraction. The crystal of the new compound is of triclinic system, space group P-1 with a=9.7919(16), b=11.0932(18), c=11.2534(19) , α=76.927(3), β=67.452(3), γ=84.895(3)°, V=1099.7(3) 3, Z=2, Dc=1.369 g/cm3, μ=1.886 mm-1, F(000)=464, R=0.0586 and wR=0.1562 for 3145 observed reflections with Ⅰ 2σ(Ⅰ). π-π Stacking interactions contribute to the stability of the structure.     

Synthesis of stereospecifically labeled carbohydrates: Preparation of (3S)− and (3R)-[3-2H1]ascarylose

The general problem of the synthesis of 3,6-dideoxy sugars containing stereospecifically labeled hydrogen isotope at C-3 is addressed for the specific case of ascarylose (3,6-dideoxy-L-arabino-hexose).     

Synthesis and Anti-HIV Activity of Further Examples of 1-[3-Deoxy-3-(N-hydroxyamino)-β-d-threo-(and β-d-erythro)-pentofuranosyl]thymine Derivatives1

Abstract

Upon sodium cyanoborohydride reduction followed by de-O-silylation, the O-methyloxime and N-benzylnitrone of 5′-TBDMS-3′-ketothymidine gave resolvable epimeric mixtures of 1-[2,3-dideoxy-3-(N-methoxyamino)-β-d-threo-and β-d-erythro-pentofuranosyl]thymine and 1-[3-(N-benzyl-N-hydroxyamino)-2,3-dideoxy-β-d-threo- and β-d-erythro-pentofuranosyl]thymine respectively. These compounds were inactive against HIV. On the other hand, 1-[2,3-dideoxy-3-(N-hydroxyamino)-5-O-TBDMS-β-d-threo-pentofuranosyl]thymine, upon treatment with acetone, then de-O-silylation, gave the bicyclonucleoside analogue 15, slightly more active against HIV in vitro than DDI.