Synthesis and molecular structure of cisoid and transoid isomers of [Re2(CO)6(1,1′-bis(indenylidene)] derived from the reaction of [Re2(CO)8(MeCN)2] and diazoindene

The compound [Re₂(CO)₈(MeCN)₂] reacts with diazoindene (C₉H₆N₂) while refluxing in THF to afford three dirhenium products in which C₉H₆N₂ is cleaved with loss of N₂ and with incorporation of the residual indenylidene group into the products. Two indenylidene groups are coupled in two diastereomers of [Re₂(CO)₆(μ,η⁵:η⁵-1,1′-C₁₈H₁₂)] where C₁₈H₁₂=bis(indenylidene). X-ray structures show that these isomers are related as RR/SS and RS isomers. These have the two Re(CO)₃ groups coordinated transoid and cisoid, respectively to a trans bis(indenylidene) bridge. The third product is the μ-indenylidene complex [Re₂(CO)₈(μ,η¹:η⁵-C₉H₆)], which was also structurally characterised by X-ray diffraction.     

Synthesis and Structure of a Bipyridyldicarboxylate Connected Neodyminum Organic Framework

The porous neodymium coordination polymer {[L₃Nd₂(H₂O)₄] (LH₂ = 2,2′‐bipyridine‐5,5′‐dicarboxylic acid)} ( 1 ) was prepared via a hydrothermal synthesis approach starting from Nd(NO₃)₃·6H₂O and 2,2′‐bipyridine‐5,5′‐dicarboxylic acid in a one to one mixture of ethanol and water at 160°C. The product was characterized by single crystal X‐ray diffraction, TGA and elemental analysis. Space group: P , a: 6.0294(4), b: 10.9061(6), c: 13.8392(9) Å, α: 101.486(7), β: 93.799(8)°, γ: 100.933(7)°, R1 [> 2σ (I)] = 0.0147, wR2 (all data) = 0.0328. The structure determination revealed 1 to be a 3‐dimensional network with eight‐coordinated lanthanide centres acting as 5‐connectors and two types of bipyridyldicarboxylate cross‐linkers, as 3‐ and a 4‐connectors. After the loss of water – two per neodymium atom‐channels are formed with a channel diameter of 4.82 Å [atom to atom distances (Nd‐O)].     

Trapping of a Thiocarbonyl Ylide with Imidazolethiones,Pyrimidinethione, and Thioamides

The reactions of 1,1,3,3-tetramethyl-8-thia-5,6-diazaspirol[3.4]oct-5-en-2-one ( 1a ) with imidazole-2-thiones 3 and pyrimidine-2(1H)-thione ( 6 ) in CHCl₃ at 40 – 50° yield 2,2,4,4-tetramethylcyclobutanone dithioacetals of type 4 and 7 , respectively, by interception of the intermediate thiocarbonyl ylide 2a (Scheme 2). Thiirane 5 is formed as a minor product by 1,3-dipolar electrocyclization of 2a . When thioacetamide ( 8a ) and thiobenzamide ( 8b ) are used as trapping reagents, the primary adduct 10 undergoes a spontaneous cyclization by intramolecular nucleophilic addition of the imino group at the carbonyl group to yield bicyclic products of type 9 . The structure of 9a has been established by X-ray crystallography.     

9-(2′-Deoxy-β-D-xylofuranosyl)adenine Building Blocks for Solid-Phase Synthesis and Properties of Oligo(2′-deoxy-xylonucleotides)

The 9-(2′-deoxy-à-D -threo-pentofuranosyl)adenine (=9-(2′-deoxy-à-D -xylofuranosyl)adeninc, xA_d; 2) was protected at its 6-NH₂ group with cither a benzoyl ( 5a ) or a (dimethyfamino)methylidcnc ( 6a ) residue and with a dimethoxytntyl group at 5′-OH ( 5b, 6b ). Compounds 5b and 6b were then converted into the 3′-phosphonates 5c and 6c ; moreover, the 2-cyanoethyl phosphoramidite 6d was synthesized starting from fib. The DNA building blocks were used for solid-phase synthesis of d[(xA)₁₂2-A] ( 8 ). The latter was hybridized with d[(xT)12-T] (T_m = 35°); in contrast, with d(T₁₂), complex formation was not observed. Moreover, xAd and xTd were introduced into the self-complementary dodccamcr d(G-T-A-G-A-A-T-T-C-T-A-C) ( 12 ) at different positions lo give the oligomcrs 13 – 16 . All oligonucleotides were characterised by temperature-dependent CD and UV spectroscopy, and in addition, 14 by T-jump experiments. From concentration-dependent T_m measurements, the thermodynamic paraneters of the melting as well as the tendency of hairpin formation of the oligonucleotides were deduced. Oligemer 14 was hydrolyzed by snake-venom phosphodiesterase in a discontinuous way implying a fast hydrolysis of unmodified 3′- and 5′-flanks followed by a slow hydrolysis of the remaining modified tetramer. In contrast to this, oligonucleotide 16 was hydrolyzed in a continuous reaction. In both cases, calf-spleen phosphodiesterase hydrolyzed the oligomer only marginally.     

Synthesis and pancreatic lipase inhibitory activities of some 1,2,4-triazol-5(3)-one derivatives

In this study, starting from 4-amino-5-(4-chlorobenzyl)-2,4-dihydro-3H-1,2,4-triazole-3-one ( 1 ), the 4-Amino-5-(4-chlorobenzyl)-2-undecyl-2,4-dihydro-3H-1,2,4-triazol-3-one ( 2 ) was first synthesized and this compound was converted to Schiff base derivatives ( 3a-e ). In the second step of the study, the 2-[3-(4-chlorobenzyl)-5-oxo-1-undecyl-1,5-dihydro-4H-1,2,4-triazole-4-yl]-acetohydrazide ( 6 ), which was used as a key product in the synthesis of many heterocyclic compounds was synthesized in four steps, and then this compound was converted into methylidene acetohydrazide ( 7a-e ), thiosemicarbazide ( 8a-e ), and 1,2,4-triazole-5-thione ( 9a-e ) derivatives. Also, in the last part of the study, 1,2,4-triazole-5-thione derivatives were changed into Mannich bases ( 10a-b ) bearing a 4-phenylpiperazine ring. These new compounds were tested with regard to pancreatic lipase (PL) inhibition activity, and compound 3b , 3d , 7d , 8d , and 9d showed a considerable anti-lipase activity at various concentrations. The activity of compounds 7b (IC₅₀ = 1.45 ± 0.12 μM) was the highest in terms of IC₅₀, comparable to that of orlistat, a well-known PL inhibitor used as an antiobesity drug.     

Ein synthetisches Modell für die Aktivstelle der Coenzym-B12-abhängigen Methylmalonyl-CoA-Mutase

A synthetic model of the active site of the coenzyme B₁₂ dependent methylmalonyl-CoA mutase The synthesis of a bridged cobaloxime with a built-in methylmalonic ester moiety is described. 2-Brommethyl-2-methylmalonic acid dichloride ( 5 ) afforded upon reaction with 5-heptin-1-ol ( 4 ) the corresponding diester 6 . Subsequent treatment of 6 with ozone, dimethylsulfide and hydroxylamine hydrochloride led to the pentadentate ligand: 10-brommethyl-10-methyl-9, 11-dioxo-8, 12-dioxa-nonadecane-2, 3, 17, 18-tetraone tetraoxime ( 8 ). Reaction of 8 with cobalt (II) chloride, pyridine and sodium borohydride furnished in 7% yield the bridged cobaloxime 10 , which was spectroscopically characterized. Short term irradiation of 10 in methanol caused the exchange of the axial pyridine ligand by a solvent molecule affording 10a , the structure of which has been determined by X-ray crystallography. Long term irradiation of 10 in methanol or ethanol led to irreversible cleavage of the Co, C-bond. Upon alkaline hydrolysis the degradation product afforded methylsuccinic acid in 82–95% yield. No incorporation of solvent protons into this product could be observed. Implications of these findings for the mechanism of the coenzyme-B₁₂ catalysed rearrangement of methylmalonyl-CoA are discussed.     

Antiproliferative Efficacy of N-(3-chloro-4-fluorophenyl)-6,7-dimethoxyquinazolin-4-amine,DW-8, in Colon Cancer Cells Is Mediated by Intrinsic Apoptosis

A novel series of 4-anilinoquinazoline analogues, DW (1–10), were evaluated for anticancer efficacy in human breast cancer (BT-20) and human colorectal cancer (CRC) cell lines (HCT116, HT29, and SW620). The compound, DW-8, had the highest anticancer efficacy and selectivity in the colorectal cancer cell lines, HCT116, HT29, and SW620, with IC₅₀ values of 8.50 ± 2.53 µM, 5.80 ± 0.92 µM, and 6.15 ± 0.37 µM, respectively, compared to the non-cancerous colon cell line, CRL1459, with an IC₅₀ of 14.05 ± 0.37 µM. The selectivity index of DW-8 was >2-fold in colon cancer cells incubated with vehicle. We further determined the mechanisms of cell death induced by DW-8 in SW620 CRC cancer cells. DW-8 (10 and 30 µM) induced apoptosis by (1) producing cell cycle arrest at the G2 phase; (2) activating the intrinsic apoptotic pathway, as indicated by the activation of caspase-9 and the executioner caspases-3 and 7; (3) nuclear fragmentation and (4) increasing the levels of reactive oxygen species (ROS). Overall, our results suggest that DW-8 may represent a suitable lead for developing novel compounds to treat CRC.     

Crystal structure of three solvated Alpinumisoflavones

Single crystals of alpinumisoflavone, C₂₀H₁₆O₅, {systematic name: 5-hydroxy-7-(4 hydroxyphenyl)-2, 2-dimethyl-2H, 6H-benzo [1, 2-b: 5, 4-b′]-dipyran-6-one}, solvated with water, methanol, and ethanol, have been obtained. The incorporation of the solvent molecules into the crystal structure creates a new short inter-molecular O–H···O and C–H···O contacts between the alpinumisoflavone moiety and its solvate molecule. The temperatures at which the solvated molecules lose their solvent molecules are 53, 54, and 65 °C for water, methanol, and ethanol, respectively. The observed temperatures at which the solvates efflorescence are reflective of the progressive increase in mass of the solvates from water to ethanol in the series. The benzopyrone moiety shows the usual planar conformation with the pyran ring deformed into a half-chair conformer as seen previously in the other analogous compounds with puckering parameters [Å], 0.2656(8), 0.3703(8), and 0.3957(9), respectively, for the water, ethanol, and methanol solvates. These are higher than the non-solvated alpinumisoflavone compound previously studied. The size of a substituent group proximal to the keto group has a more pronounced effect on the degree of puckering than substitution on the terminal phenyl ring. The attached phenyl ring shows consistent out-of-plane twist from the mean plane of the benzopyrone system as observed previously for this class of compounds. The observed dihedral angles are 30.26(3), 37.75(3), and 34.00(3)°, respectively, for the water, methanol, and ethanol solvates.     

Synthesis and in vitro anticancer activity of some novel cyclohepta[b]thiophene-3-carboxamides bearing pyrazole moiety

2-Aminothiophene 3 was achieved through the one-pot multicomponent reaction of cycloheptanone, cyanoacetamide, elemental sulfur, and morpholine in ethanol. Diazotization of 2-aminothiophene 3 with NaNO₂/HCl gave the corresponding diazonium salt 4 , that combined with the appropriate active methylene components; 5a , 5b , 7 , 11 , 13 , 16 , 18 , 21 , 9 , 19 , 22a , and 22b in pyridine (AcONa/EtOH) to form the corresponding hydrazones 6a , 6b , 8 , 10 , 14 , 15 , 17 , 20 , 23 , 24 , 25a , and 25b , respectively. Heating of compound 8 with malononitrile 9 in ethanol gave the thiazole 10 . Treatment of compound 10 , 25a , and 25b with hydrazine hydrate achieve the pyrazoles 12 , 27a , and 27b , respectively. Hydrazinolysis of compound 14 with hydrazine hydrate, followed by condensation of the obtained hydrazide 15 with acetylacetone 19 gave the pyrazole 20 . The recently orchestrated thiophenes were assessed for their cytotoxic action. The result revealed that compound 12 indicated comparable and better action towards HePG2, HCT-116, MCF-7, and PC3 cancer cell lines than Doxorubicin.     

Selective Isomerization of Epoxides to Allylic Alcohols Catalyzed by TiO2‐Supported Gold Nanoparticles

ReacTiO ₂ ns for rings : Gold nanoparticles supported on TiO₂ are used as a novel heterogeneous catalyst for the isomerization of epoxides to allylic alcohols by a concerted mechanism (see scheme). The reaction proceeds in high yields and the product selectivity is often remarkable.

     

The reaction of Ru3(CO)12 with HC9PPh2)3. Characterisation of Ru3(CO)9[HC(PPh2)3], and crystal and molecular structure of Ru3(CO)9[HC(PPh2)(PhPC6H4PPh)]·CHCl3

Reaction of Ru₃(CO)₁₂ with HC(PPh₂)₃ leads to a variety of products, two of which have been characterised. One is the symmetrically capped product Ru₃(CO)₉[HC(PPh₂)₃], which was characterised spectroscopically. The second product was characterised crystallographically as Ru₃(CO)₉[HC(PPh₂)-(PhPC₆H₄PPh)]-CHCl₃.     

Cyclization reactions of long-lived 10,10-dimethyl-9-phenylethynyl-9,10-dihydrophenanthren-9-yl cation

According to the NMR data, long-lived 10,10-dimethyl-9-phenylethynyl-9,10-dihydrophenanthren-9-ylium in acid medium undergoes cyclization whose direction is determined by the acidity of the medium. The cyclization in HSO₃F-SbF₅ superacid involves the aromatic ring in the phenanthrene core as nucleophilic component and yields 5a,6-dimethyl-4-phenyl-4,5,5a,6-tetrahydroacephenantrylene-4,6-bis(ylium). In trifluoroacetic acid the nucleophilic component is the side-chain phenyl group, and the cyclization product is neutral 8b,14b-dimethyl-8b,14b-dihydrobenzo[g]chrysen-10-yl trifluoroacetate. Both cyclization directions are observed in moderate-strength trifluoromethanesulfonic acid.     

The reactions of tetrafluoroethylene oligomers: V. The reactions of perfluoro-3,4-dimethyl-4-ethylhexene-(2) with thionucleophiles and the chemical transformations of reaction products

The reactions of perfluoro-3,4-dimethyl-4-ethylhexene-(2) (1) with s-nucleophiles such as benzylthiol, allylthiol, phenylthiol and the chemical transformations of these reaction products were reported. 1 reacted with S-nucleophiles to give four types of isomeric products. At ?30～ ?60°C, in ether, kinetically controlled product 2 (a, b, c) were formed. Compound 2 might be converted directly into the thermodynamically stable products 3 (a, b,) in DMF-KF at r.t., At 100°C, 2 was converted to 4 (a, b, c) via intramolecular rearrangement. In KF-DMF at r.t., 4 was isomerized to 5 (a, b, c). 2a also reacted with another mole of thiol to give the corresponding disulfide 6 and hydrogen-containing olefin 7a as well as the disubstituted product 8a in DMF, but only give 3a and 9a in ether-Et₃N. The reaction of 2a with methyl alcohol gave only a small amounts of 3a and 10a. The reaction of 2b with dimethylamine was complex and 3b and 11 were obtained in low yield.     

Reactions of p-quinone monoimines with lawesson reagent and phosphorus pentasulfide

2, 4-Bis-(4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane-2, 4-disulfide [Lawesson reagent (LR)] 1 reacts with p-quinone monoimine- 2a to give the novel benzo-1,3,2-oxathiaphosphol-5-(methanesulfonamido)-2-(4-methoxyphenyl)-2-sulfide 4 . On the other hand, the reaction of 2b and 3 with LR 1 leads to the formation of the benzo- and the naphtho-1,3,2-dithiaphosphol-5 -(benzenesulfonamido)- 2- (4-methoxyphenyl) -2-sulfide 5 , 6 . Thiation of 2a , 2b , and 3 with P₄S₁₀ yields phenoxathiin derivatives 8a , 8b , and 9 , respectively. The identity of the new products is established from analytical and spectroscopic evidence.     

Synthese von Trifluoromethyl-substituierten Schwefel-Heterocyclen unter Verwendung von 3,3,3-Trifluorobrenztraubensäure-Derivaten

Synthesis of Trifluoromethyl-Substituted Sulfur Heterocycles Using 3,3,3-Trifluoropyruvic-Acid Derivatives The reaction of methyl 3,3,3-trifluoropyruvate ( 1 ) with 2,5-dihydro-1,3,4-thiadiazoles 4a, b in benzene at 45° yielded the corresponding methyl 5-(trifluoromethyl)-1,3-oxathiolane-5-carboxylates 5a, b (Scheme 1) via a regioselective 1,3-dipolar cycloaddition of an intermediate ‘thiocarbonyl ylide’ of type 3 . With methyl pyruvate, 4a reacted similarly to give 6 in good yield. Methyl 2-diazo-3,3,3-trifluoropropanoate ( 2 ) and thiobenzophenone ( 7a ) in toluene underwent a reaction at 50°; the only product detected in the reaction mixture was thiirane 8a (Scheme 2). With the less reactive thiocarbonyl compounds 9H-xanthene-9-thione ( 7b ) and 9H-thioxanthene-9-thione ( 7c ) as well as with 1,3-thiazole-5(4H)-thione 12 , diazo compound 2 reacted only in the presence of catalytic amounts of Rh₂(OAc)₄. In the cases of 7a and 7b , thiiranes 8b and 8c , respectively, were the sole products (Scheme 3). The crystal struture of 8c has been established by X-ray crystallography (Fig.). In the reaction with 12 , desulfurization of the primarily formed thiirane 14 gave the methyl 3,3,3-trifluoro-2-(4,5-dihydro-1,3-thiazol-5-ylidene)propanoates (E)-and (Z)- 15 (Scheme 4). A mechanism of the Rh-catalyzed reaction via a carbene addition to the thiocarbonyl S-atom is proposed in Scheme 5.     

Monomers for Adhesive Polymers, 6

Summary: 1,3‐Bis(methacrylamido)propane‐2‐yl dihydrogen phosphate ( 1 ) was synthesised by phosphorylation of 1,3‐bis(methacrylamido)‐2‐hydroxypropane ( 2 ) with phosphorus oxychloride in tetrahydrofuran (THF) in the presence of triethylamine (TEA). The structure of the new monomer 1 was characterised by IR, ¹H NMR, ¹³C NMR and ³¹P NMR spectroscopies, elemental analysis and mass spectrometry. The monomer dissolves well in water, ethanol or aqueous THF and shows an improved hydrolytic stability compared to the corresponding methacrylate‐based dihydrogen phosphates. 1 was homopolymerised in ethanol with 2,2′‐azoisobutyronitrile (AIBN) as the initiator at 55–75 °C under the formation of an insoluble, cross‐linked product. Aqueous solutions of 1 are strongly acidic and enable to etch enamel and dentin. Nevertheless, 1 did not show any cytotoxic effect. Furthermore, the adhesive properties of 1 were measured.

1,3‐Bis(methacrylamido)propane‐2‐yl dihydrogen phosphate.     

Unusual Pathway Taken in the Reaction of Bis(alkynyl)diisopropylaminoboranes with B(C6F5)3

The bis(alkynyl)diisopropyl‐aminoboranes 7 were prepared by treatment of iPr₂NBCl₂ with two molar equivalents of 1‐pentynyl lithium or lithium phenylacetylenide, respectively. Their reaction with one molar equivalent of B(C₆F₅)₃ resulted in the formation of the 1,1‐carboboration products 8 that were subsequently stabilized by adduct formation ( 9 ) with tert‐butyl isocyanide. Thermolysis of 8a (R=nPr) proceeded with hydride transfer from a N‐isopropyl substituent to the distal carbon atom of the remaining pentynyl unit at boron to give the zwitterionic five‐membered heterocyclic product 10a in good yield. The analogous product 10b (R=Ph) was obtained upon photolysis of 8b . The compounds 7b , 9b , 10a , and 10b were characterized by X‐ray crystal structure analysis.     

Highly Efficient and Facile Photocatalytic Recycling System Suitable for ICAR ATRP of Hydrophilic Monomers

Photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (ATRP) of hydrophilic monomers in heptane/ethanol latent‐biphasic system for copper catalyst separation and recycling have been realized for the first time at room temperature with different wavelengths of visible light LED (green, blue, purple, and white LED) as external stimulus, using 2‐bromophenylacetate as the ATRP initiator and camphorquinone/triethylamine as the photoinitiator. In this system, hybrid catalyst complex (HCc) is synthesized as a novel nonpolar catalyst, which is preferentially dissolved in heptane. The hydrophilic polymers obtained catalyzed by HCc in heptane/ethanol mixture solvent show typical “living” features, for example, the values of M_n,GPC increase linearly with monomer conversion up to quantitative level (>96%) and the molecular weight distributions were kept narrow (M_w/M_n < 1.20) throughout the polymerization process. It should be noted that the excellent controllability of this novel polymerization system can be achieved even after 5 catalyst recycling experiments under LED irradiation.

     

Synthetic Control and Multifunctional Properties of Fluorescent Covalent Triazine‐Based Frameworks

Conjugated microporous polymers (CMPs), with the virtue of high porosity and optoelectronic activity, are attracting increasing research interest and have been used in various environmental and energy areas. Efficient synthesis and the exploitation of new functionalities are the research hotspots in the CMPs research area. Covalent triazine frameworks (CTFs) synthesized by CF₃SO₃H catalyzed trimerization reactions show properties quite alike to CMPs and this method avoids the use of noble metal catalysts. In this study, a series of novel fluorescent covalent triazine‐based frameworks (F‐CTFs) is prepared using different tetra‐cyano compounds as the starting monomers. Both porosity and fluorescence properties of the F‐CTFs can be adjusted by the monomer structure. Gas adsorption measurement reveals that F‐CTF1 with the largest surface area of 896 m² g⁻¹ shows the highest CO₂ uptake of 3.29 mmol g⁻¹ at 273 K and 1.13 bar among the polymers. Taking advantages of their large surface areas and strong fluorescence, these F‐CTFs could be used as efficient chemical sensing agents for various nitroaromatic compounds as well.

     

Polyaniline Fan‐Like Architectures of Rectangular Sub‐Microtubes Synthesized in Dilute Inorganic Acid Solution

Rectangular‐tube‐based fan‐like polyaniline has been readily fabricated by the oxidation polymerization of low‐concentration aniline in dilute HCl aqueous solution for the first time. Different from the conventional polymerization that proceeds in concentrated acidic solution (to produce nanofibers), this synthesis was conducted in dilute inorganic acid solution at room temperature and created polyaniline hierarchical fan‐like architectures. The morphological evolution of the product has been followed with respect to the reaction time, based on which conceivable interpretations of the formation of rectangular tubes and their assembly into fan‐like architectures are given. Other inorganic acids (HNO₃, H₂SO₄, and H₃PO₄) with low concentrations have been used to replace HCl in the reaction system to validate the adaptability of this approach in this report.