Polyaniline salts and complexes: Efficient and reusable catalyst for the one‐pot synthesis of 5‐(methoxycarbonyl)‐6‐methyl‐4‐phenyl‐3,4‐dihydropyrimidin‐2(1h)‐one

Polyaniline salts were prepared by doping polyaniline base with different Bronsted acids (sulfuric, nitric, phosphoric, perchloric, hydrochloric acid) and organic acids (p‐toluene sulfonic acid, 5‐sulfosalicylic acid). Polyaniline complexes were also prepared using Lewis acids (aluminum chloride, ferric chloride). Polyaniline salts and polyaniline complexes were used as catalysts in Biginelli reaction for 5‐(methoxycarbonyl)‐6‐methyl‐4‐phenyl‐3,4‐dihydropyrimidin‐2(1H)‐one synthesis. Benzaldehyde and urea were reacted with methyl acetoacetate using polyaniline‐p‐toluene sulfonate salt as catalyst with different reaction time, temperature, and amount of catalyst. The use of polyaniline catalysts is feasible because of the easy preparation, easy handling, stability, easy recovery, simple work‐up procedure, reusability, excellent activity with less amount of catalyst, and eco‐friendly nature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1741–1745, 2006     

Head‐to‐Head Homo‐Coupling of Arylethynes Catalysed by (Dicarbonyl)ruthenium Chloride Metallacycles: Selective Synthesis of (E)‐1,4‐Diarylbut‐1‐en‐3‐ynes

Exposure of various arylethynes to catalytic amounts of dimeric ruthenacycles containing the chloro(dicarbonyl)ruthenium [Ru(CO)₂Cl] motif efficiently and selectively leads to the formation of (E)‐1,4‐diaryl‐but‐1‐en‐3‐ynes that result from head‐to‐head C C coupling.     

Ethylene/1‐octadecene copolymerization using [η5:η1‐C5Me4‐4‐R1‐6‐R‐C6H2O]TiCl2 catalysts

Copolymerization of ethylene with 1‐octadecene was studied using [η⁵:η¹‐C₅Me₄‐4‐R₁‐6‐R‐C₆H₂O]TiCl₂ [R₁ = ^tBu (1), H (2, 3, 4); R = ^tBu (1, 2), Me (3), Ph (4)] as catalysts in the presence of Al(i‐Bu)₃ and [Ph₃C][B(C₆F₅)₄]. The effect of the concentration of comonomer in the feed and Al/Ti molar ratio on the catalytic activity and molecular weight of the resultant copolymer were investigated. The substituents on the phenyl ring of the ligand affect considerably both the catalytic activity and comonomer incorporation. The 1 /Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄] catalyst system exhibits the highest catalytic activity and produces copolymers with the highest molecular weight, while the 2 /Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄] catalyst system gives copolymers with the highest comonomer incorporation under similar conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Basic characterization of polypropene‐block‐poly(methylene‐1,3‐cyclopentane‐co‐propene) synthesized from propene and 1,5‐hexadiene with modified stopped‐flow method

Block copolymerization of propene and 1,5‐hexadiene was carried out by a modified stopped‐flow polymerization method with an MgCl₂‐supported Ziegler catalyst. The resulting polymer, polypropene‐block‐poly(methylene‐1,3‐cyclopentane‐co‐propene) (PP‐b‐(PMCP‐co‐PP)), in which the crystallizable PP part was linked with the non‐crystallizable PMCP‐co‐PP part, was characterized by optical microscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing. The block copolymer having a chemical linkage between PP and PMCP‐co‐PP showed properties different from those of homopolymer, random copolymer and blend polymer. © 2001 Society of Chemical Industry     

Catalytic Asymmetric Hydrogenation of α‐Arylcyclohexanones and Total Synthesis of (−)‐α‐Lycorane

An efficient catalytic asymmetric hydrogenation of racemic α‐arylcyclohexanones with an ethylene ketal group at the 5‐position of the cyclohexane ring via dynamic kinetic resolution has been developed, giving chiral α‐arylcyclohexanols with two contiguous stereocenters with up to 99% ee and >99:1 cis/trans‐selectivity. Using this highly efficient asymmetric hydrogenation reaction as a key step, (−)‐α‐lycorane was synthesized in 19.6% overall yield over 13 steps from commercially available starting material.     

Continuous Hydrogenation of Toluene over Sr‐ and PEG800‐Modified Ni/γ‐Al2O3 Catalysts

A series of γ‐Al₂O₃‐supported nickel‐based catalysts were evaluated in continuous hydrogenation of toluene. Sr‐ and poly(ethylene glycol) 800 (PEG800)‐modified Ni/γ‐Al₂O₃ catalysts provided the best activity with high conversion of toluene and selectivity for methylcyclohexane which was ascribed to the addition of Sr and PEG800 during the preparation process, resulting in smaller and highly dispersed Ni species on the surface and in the pores of γ‐Al₂O₃. Furthermore, the formation of SrCO₃ and NiAl₂O₄ is believed to be advantageous for the dispersion and stabilization of the active Ni species, accounting for its good stability.     

Catalyst‐Free Domino Reaction of 1‐Acryloyl‐1‐N‐arylcarbamylcyclopropanes with Amines: One‐Pot Approach to 2,3,6,7‐Tetrahydro‐1H‐pyrrolo[3,2‐c]pyridin‐4(5H)‐ones

A facile one‐pot, catalyst‐free reaction has been developed for the synthesis of 2,3,6,7‐tetrahydro‐1H‐pyrrolo[3,2‐c]pyridin‐4(5H)‐ones from readily available 1‐acryloyl‐1‐N‐arylcarbamylcyclopropanes and amines using a domino ring‐opening/cyclization/aza‐addition sequence.

     

Silver‐Catalyzed Intramolecular Cyclization of o‐(1‐Alkynyl)benzamides: Efficient Synthesis of (1H)‐Isochromen‐1‐imines

An efficient avenue for the facile and atom‐economic synthesis of (1H)‐isochromen‐1‐imines has been developed, and a broad spectrum of substrates can participate in the process effectively to produce the desired products in good yields. Significantly, this is the first report of the synthesis of (1H)‐isochromen‐1‐imines that involves a silver(I)‐catalyzed, regiocontrolled intramolecular addition of the carbonyl group of the amide moiety towards an alkyne.     

Synthesis of 6‐amino acid substituted 4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizines

In the presence of Na₂CO₃ (1S,3S)‐ and (1R,3S)‐1‐(2,2‐dimethoxyethyl)‐2‐(1,3‐dioxobutyl)‐3‐(1,3‐dioxo‐butyl)oxymethyl‐1,2,3,4‐tetrahydrocarboline ( 1 ) were transformed into (1S,3S)‐ and (1R,3S)‐1‐(2,2‐dimethoxyethyl)‐2‐(1,3‐dioxobutyl)‐3‐hydroxymethyl‐1,2,3,4‐tetrahydrocarboline ( 2 ), which were cyclized to (6S)‐3‐acetyl‐6‐hydroxymethyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizine ( 4 ), via(6S,12bS)‐ and (6S,12bR)‐3‐acetyl‐2‐hydroxyl‐6‐hydroxymethyl‐1,2,3,4,6,7,12,12b‐octahydro‐4‐oxoindolo[2,3‐a]quinoline ( 3 ). (6S)‐ 4 was coupled with Boc‐Gly, Boc‐L‐Asp(β‐benzyl ester), or Boc‐L‐Gln to give 6‐amino acid substituted (6S)‐3‐acetyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizines 5a , 5b , or 5c , respectively. After the removal of Boc from (6S)‐ 5a (6S)‐3‐acetyl‐6‐glycyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizine ( 6 ) was obtained. The anticancer activities of (6S)‐ 5 and (6S)‐ 6 in vitro were tested.     

Ligand‐Free Copper‐Manganese Spinel Oxide‐Catalyzed Tandem One‐Pot C–H Amidation and N‐Arylation of Benzylamines: A Facile Access to 2‐Arylquinazolin‐4(3H)‐ones

An efficient ligand‐free copper‐manganese (Cu‐Mn) spinel oxide‐catalyzed direct tandem C−H oxygenation and N‐arylation of benzylamines has been developed. The method has been utilized for the synthesis of medicinally important 2‐arylquinazolin‐4(3H)‐ones. Salient features of this method include recyclable catalyst, no ligand, excellent product yields, shorter reaction times and a broad substrate scope.

     

Synthesis of acrylamide end‐functionalised poly(1‐hexene) using an α‐diimine nickel catalyst

The nickel precursor [bis(N,N′‐dimesitylimino)acenaphthene]dibromonickel and methylaluminoxane were used to catalyse the functionalisation of 1‐hexene with acrylamide by passivation of acrylamide with tri‐isobutylaluminium. The polymer obtained was characterised by GPC/SEC and NMR. The NMR experiments performed, COSY, DEPT, long‐range selective INEPT, HSQC and TOCSY 1D, showed that a 2,1 insertion of a single molecule of acrylamide per macromolecule had occurred at the end of the polyhexene chain. Copyright © 2004 Society of Chemical Industry     

O6‐Alkylguanine‐DNA Alkyltransferase‐Mediated Repair of O4‐Alkylated 2′‐Deoxyuridines

O⁶‐Alkylguanine‐DNA alkyltransferases (AGTs) are responsible for the removal of O⁶‐alkyl 2′‐deoxyguanosine (dG) and O⁴‐alkyl thymidine (dT) adducts from the genome. Unlike the E. coli OGT (O⁶‐alkylguanine‐DNA‐alkyltransferase) protein, which can repair a range of O⁴‐alkyl dT lesions, human AGT (hAGT) only removes methyl groups poorly. To uncover the influence of the C5 methyl group of dT on AGT repair, oligonucleotides containing O⁴‐alkyl 2′‐deoxyuridines (dU) were prepared. The ability of E. coli AGTs (Ada‐C and OGT), human AGT, and an OGT/hAGT chimera to remove O⁴‐methyl and larger adducts (4‐hydroxybutyl and 7‐hydroxyheptyl) from dU were examined and compared to those relating to the corresponding dT species. The absence of the C5 methyl group resulted in an increase in repair observed for the O⁴‐methyl adducts by hAGT and the chimera. The chimera was proficient at repairing larger adducts at the O⁴ atom of dU. There was no observed correlation between the binding affinities of the AGT homologues to adduct‐containing oligonucleotides and the amounts of repair measured.     

High cis‐1,4 polyisoprene or cis‐1,4/3,4 binary polyisoprene synthesized using 2‐(benzimidazolyl)‐6‐(1‐(arylimino)ethyl)pyridine cobalt(II) dichlorides

Polyisoprene (PI) with a high content of cis‐1,4 (up to 95%) or cis‐1,4/3,4 binary structures was synthesized using a cobalt system in toluene. The cobalt system, which exhibited high activities (up to 3.50 × 10⁶ g PI (mol Co)^?1 h^?1), contained a series of 2‐(benzimidazolyl)‐6‐(1‐(arylimino)ethyl)pyridine cobalt(II) dichlorides activated with ethylaluminium sesquichloride. The nature of the ligands and the reaction conditions significantly affected both the catalytic performance of the cobalt complexes as well as the structures of the resultant PI. The stereospecific polymerization of isoprene could be tuned via changing either the co‐catalyst or solvent: for example, increased content of 3,4 PI (up to 36.6%) was achievable in heptane in the presence of diethylaluminium chloride. Sequence distribution analysis by ¹³C NMR spectroscopy indicated that most 3,4 units occurred randomly in the PI chains. © 2013 Society of Chemical Industry     

siRNA Modified with 2′‐Deoxy‐2′‐C‐methylpyrimidine Nucleosides

(2′S)‐2′‐Deoxy‐2′‐C‐methyluridine and (2′R)‐2′‐deoxy‐2′‐C‐methyluridine were incorporated in the 3′‐overhang region of the sense and antisense strands and in positions 2 and 5 of the seed region of siRNA duplexes directed against Renilla luciferase, whereas (2′S)‐2′‐deoxy‐2′‐C‐methylcytidine was incorporated in the 6‐position of the seed region of the same constructions. A dual luciferase reporter assay in transfected HeLa cells was used as a model system to measure the IC₅₀ values of 24 different modified duplexes. The best results were obtained by the substitution of one thymidine unit in the antisense 3′‐overhang region by (2′S)‐ or (2′R)‐2′‐deoxy‐2′‐C‐methyluridine, reducing IC₅₀ to half of the value observed for the natural control. The selectivity of the modified siRNA was measured, it being found that modifications in positions 5 and 6 of the seed region had a positive effect on the ON/OFF activity.     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

Improved conversion of 6‐endo‐tosyloxybicyclo[2.2.2]octan‐2‐ones into 6‐exo‐acetoxy and 6‐exo‐benzoyloxybicyclo[2.2.2]octan‐2‐ones

The reaction conditions for the conversion of 6‐endo‐tosyloxybicyclo[2.2.2]octan‐2‐one ( 7b ) into 6‐exo‐acetoxy ( 8b ) and 6‐exo‐benzoyloxybicyclo[2.2.2]octan‐2‐one ( 8a ), respectively, were improved. Thus known 6‐endo‐tosyloxy‐bicyclo[2.2.2]octan‐2‐ones (+)‐(1RS,6SR,8SR,11RS)‐11‐[(4‐toluenesulfonyl)oxy]tricyclo[6.2.2.0^1,6]dodecan‐9‐one ( 1a ), 13‐methyl‐15‐oxo‐9β,13b‐ethano‐9β‐podocarpan‐12β‐yl‐4‐toluenesulfonate ( 3a ), and methyl (13R)‐16‐oxo‐13‐[(4‐tolylsulfonyl)oxy]‐17‐noratisan‐18‐oate ( 5 ), were converted,in comparable yields, as previously recorded, but much shorter times, into (+)‐(1RS,6SR,8SR,11SR)‐11‐(benzoyloxy) tricyclo[6.2.2.0^1,6]dodecan‐9‐one ( 2 ), 13‐methyl‐15‐oxo‐9β,13β‐ethano‐9β‐podocarpan‐12α‐yl benzoate ( 4 ), and methyl (13S)‐13‐(benzoyloxy)‐16‐oxo‐17‐noratisan‐18‐oate ( 6 ), respectively.     

Galvanic deposition of silver on 80‐μm‐Cu‐fiber for gas‐phase oxidation of alcohols

Microstructured Ag‐based catalysts were developed by galvanically depositing Ag onto 80‐μm‐Cu‐fibers for the gas‐phase oxidation of alcohols. By taking advantages including large voidage, open porous structure and high heat/mass transfer, as‐made catalysts provided a nice combination of high activity/selectivity and enhanced heat transfer. The best catalyst was Ag‐10/80‐Cu‐fiber‐400 (Ag‐loading: 10 wt%; Cu‐fiber pretreated at 400 °C in air), being effective for oxidizing acyclic, benzylic and polynary alcohols. For benzyl alcohol, conversion of 94% was achieved with 99% selectivity to benzaldehyde at 300 °C using a high WHSV of 20 h^?1. Computational fluid dynamics (CFD) calculation and experimental result illustrated significant enhancement of the heat transfer. The temperature difference from reactor wall to central line was about 10–20 °C for the Ag‐10/80‐Cu‐fiber‐400, much lower than that of 100–110 °C for the Ag‐10‐Cu‐2/Al₂O₃ at equivalent conversion and selectivity. Synergistic interaction between Cu₂O and Ag was discussed, being assignable to the activity improvement. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1045–1053, 2014     

Synthesis,Crystal Structure,and Thermal Behaviors of 3‐Nitro‐1,5‐bis(4,4′‐dimethylazide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP)

The energetic material, 3‐nitro‐1,5‐bis(4,4′‐dimethyl azide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP), was firstly synthesized by means of Click Chemistry using 1,5‐diazido‐3‐nitrazapentane as main material. The structure of NDTAP was confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy; mass spectrometry, and elemental analysis. The crystal structure of NDTAP was determined by X‐ray diffraction. It belongs to monoclinic system, space group C2/c with crystal parameters a=1.7285(8) nm, b=0.6061(3) nm, c=1.6712(8) nm, β=104.846(8)°, V=1.6924(13) nm³, Z=8, μ=0.109 mm⁻¹, F(000)=752, and D_c=1.422 g cm⁻³. The thermal behavior and non‐isothermal decomposition kinetics of NDTAP were studied with DSC and TG‐DTG methods. The self‐accelerating decomposition temperature and critical temperature of thermal explosion are 195.5 and 208.2 °C, respectively. NDTAP presents good thermal stability and is insensitive.     

Atom transfer radical polymerization of (R)‐2‐methacryloyloxy‐2′‐methoxy‐1,1′‐binaphthalene

Atom transfer radical polymerization (ATRP) of (R)‐2‐methacryloyloxy‐2′‐methoxy‐1,1′‐binaphthalene ((R)‐MAMBN) mediated by different amine ligands, copper(I) chloride and ethyl 2‐bromopropionate in different solvents, and reverse ATRP of (R)‐MAMBN were studied. It was shown that optically active polymers were obtained, with poor control of the molecular weights, and low polydispersities. Specific rotation of the polymers increased with increasing molecular weights. By comparison with (R)‐MAMBN, poly((R)‐MAMBN)s exhibits higher specific rotation and a positive Cotton effect. Copyright © 2003 Society of Chemical Industry     

Synthesis mechanisms of poly[styrene‐co‐(acrylic acid)]‐supported TiCl4 catalysts modified by magnesium compounds

Soluble poly[styrene‐co‐(acrylic acid)] (PSA) modified by magnesium compounds was used to support TiCl₄. For ethylene polymerization, four catalysts were synthesized, namely PSA/TiCl₄, PSA/MgCl₂/TiCl₄, PSA/(n‐Bu)MgCl/TiCl₄, and PSA/(n‐Bu)₂Mg/TiCl₄. The catalysts were characterized by a set of complementary techniques including X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and element analysis. Synthesis mechanisms of polymer‐supported TiCl₄ catalysts were proposed according to their chemical environments and physical structures. The binding energy of Ti 2p in PSA/TiCl₄ was extremely low as TiCl₄ attracted excessive electrons from ? COOH groups. Furthermore, the chain structure of PSA was destroyed because of intensive reactions taking place in PSA/TiCl₄. With addition of (n‐Bu)MgCl or (n‐Bu)₂Mg, ? COOH became ? COOMg‐ which then reacted with TiCl₄ in synthesis of PSA/(n‐Bu)MgCl/TiCl₄ and PSA/(n‐Bu)₂Mg/TiCl₄. Although MgCl₂ coordinated with ? COOH first, TiCl₄ would substitute MgCl₂ to coordinate with ? COOH in PSA/MgCl₂/TiCl₄. Due to the different synthesis mechanisms, the four polymer‐supported catalysts correspondingly showed various particle morphologies. Furthermore, the polymer‐supported catalyst activity was enhanced by magnesium compounds in the following order: MgCl₂ > (n‐Bu)MgCl > (n‐Bu)₂Mg > no modifier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012