Photochemistry of cyclic vicinal tricarbonyl compounds Photolysis of alloxan in the presence of olefins containing allylic hydrogen

UV irradiation of an acetone solution of alloxan (1) in the presence of olefins containing allylic hydrogen leads to the formation of 5-hydroxy-5-alkenyl barbituric acids (2) resulting from an initial hydrogen abstraction process. On the other hand, photolysis of 1 with ethyl-1-propenyl ether yields [2+2] (oxetanes) and [4+2] (dioxenes) photocycloaddition products, beside the corresponding hydrogen abstraction products. When the irradiation was performed with olefins containing electron-acceptor substituents, product formation could not be observed.     

Mechanism of reduction of benzylidenemalono-nitrile by l-benzyl-1,4-dihydronicotinamide

The reduction of benzylidenemalononitrile by 1-benzyl-1,4-dihydronicotinamide undergoes via a one-step hydride transfer mechanism rather than a multistep mechanism involving initial electron transfer.     

Mechanism of reduction of benzylidenemalononitrile by 1-benzyl-1,4-dihydronicotinamide

The reduction of benzylidenemdononitrile by 1-benzyl-1,4-dihydronicotinamide undergoes via a one-step hydride transfer mechanism rather than a multistep mechanism involving initial electron transfer.     

Electron-transfer chain-substitution in hydrodemercuration of alkylmercury(II) compounds with n-benzyl-1,4-dihydronicotinamide

Reduction of alkylmercury(II) acetates with N-benzyl-1,4-dihydronicotinamide (BNAH) proceeds through electron-transfer chain-substitution mechanism. The rate constant of hydrogen transfer from BNAH to alkyl radical was estimated as in the order of 10⁵ 1/mol·sec.     

Synthesis and reversible hydration–dehydration system of copolymers bearing a vicinal tricarbonyl structure

Novel copolymers composed of a styrene (St) derivative bearing a vicinal tricarbonyl moiety and various vinyl monomers such as St, methyl methacrylate (MMA), and N‐vinylpyrrolidone (NVP) were synthesized by (1) radical copolymerization of a St derivative with a 1,3‐diketone structure with St, MMA, and NVP and (2) successive oxidation of the resulting copolymers with N‐bromosuccinimide in DMSO to convert their 1,3‐diketone moieties in the side chains into the corresponding vicinal tricarbonyl moieties. Their tricarbonyl moieties were readily hydrated in water‐containing acetone to generate the corresponding copolymers bearing geminal diol structures in the side chains. On the other hand, heating the resulting copolymers bearing the geminal diol structures in vacuo‐enabled successful recovery of the vicinal tricarbonyl moieties to demonstrate the reversible nature of this system. The hydration behavior in powdery state under air atmosphere saturated by water was also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A novel reaction of vicinal tricarbonyl compounds with the isocyanide-DMAD zwitterion: formation of highly substituted furan derivatives

The vicinal tricarbonyl system participates in a novel reaction with the zwitterion derived from isocyanide and dimethyl acetylenedicarboxylate to form fully substituted furan derivatives.     

Preparation and characterization of organotin-oxomolybdate coordination polymers and their use in sulfoxidation catalysis

The organotin-oxomolybdates [(R(3)Sn)(2)MoO(4)].n H(2)O (R=methyl, n-butyl, cyclohexyl, phenyl, benzyl) have been prepared and tested as catalysts for the oxidation of benzothiophene with aqueous hydrogen peroxide, at 35 degrees C and atmospheric pressure. In all cases, the 1,1-dioxide was the only observed product. The kinetic profiles depend on the nature of the tin-bound R group and also on the addition of a co-solvent. For the tribenzyltin derivative, the apparent activation energies for sulfoxidation as a function of the co-solvent are in the order 1,2-dichloroethane (5 kcal mol(-1))相似文献   

Synthesis of new linear polymers containing phosphorus atom in the main chain by the radical polyaddition: Addition polymers of phenylphosphine with 1,4-divinylbenzene or 1,4-diisopropenylbenzene and their properties

A polyaddition of phenylphosphine (PH) to 1,4-divinylbenzene (DVB) or 1,4-diisopropenylbenzene (DIPB) was carried out by radical initiations or UV irradiation at 60–80°C in toluene under a nitrogen atmosphere. The soluble polymer with higher molecular weight () was obtained in a high yield with AIBN initiator for 95 h in the presence of 5% excess of PH to DVB (monomer feed ratio [DVB]₀/[PH]₀ = 1/1.05). On the other hand, a polyaddition of PH to DIPB proceeded much slower than the case of DVB, but the high polymer was obtained in a high yield by choosing polyaddition conditions such as polyaddition temperature and initiator concentration. From ¹H-NMR, IR analyses, and phosphorus content of the polymers, it was characterized that both polymers have the alternating structure consisting of PH and DVB or DIPB units in 1 : 1 ratio. The glass transition and decomposition temperatures of both polymers under a nitrogen atmosphere were almost similar: 15–30°C and 380–385°C, respectively; but, the polymers were oxidized by heating under an atmosphere of air. The polymers had a self-extinguishing property and the polymer blend of the flammable polymers such as polystyrene and polyethylene with the phosphorus-containing polymers exhibited an excellent flame resistance. © 1994 John Wiley & Sons, Inc.     

Homolysis of the TL-C bond in hydrodethallation of alkylthallium(III) compounds with n-benzyl-1,4-dihydronicotinamide

Reduction of alkylthallium(III) compounds, RT1X₂ with N-benzyl-1,4-dihydronicotinamide to give high yields of RH compounds proceeds through homolysis of the Tl-C bond of an alkylthallium(II) intermediate formed by one-electron reduction of RT1X₂.     

Synthesis and properties of polymers containing aromatic amino groups in the main chain and their glass-forming model compounds

Polymers containing di(carbazol-3-yl)phenylamine and N,N^′-di(carbazol-3-yl)-N,N^′-diphenyl-1,4-phenylenediamine units in the main chain have been synthesized by a modified Ullmann condensation as a key step. The number-average molecular weights of the polymers synthesized were in the range of 2300-4800 with a molecular weight distribution of 1.42-2.25. Well defined model compounds of the title polymers were synthesized by stepwise reactions. All the materials exhibit high thermal stability with the initial weight loss temperatures exceeding 320 °C and form glasses. Their glass transition temperatures range from 102 to 216 °C as characterised by differential scanning calorimetry. The electron photoemission spectra of thin films of the synthesized compounds have been recorded and the ionisation potentials of 5.0-5.1 eV have been established.     

Preparation and characterization of bismaleimides containing ester groups from bisphenolic chelates and their polymers

A series of novel metal‐containing bismaleimide monomers was prepared by the reaction of 4‐maleimidobenzoic acid chloride with bisphenolic chelates. By reaction of the synthesized bismaleimides with bis(1‐mercapto‐2‐ethylether) or 3,4‐dichloromaleimidobenzoic acid chloride, new chelating polyimidosulfides and poly(ether‐ester)maleimides were prepared. The structures of the bisphenols, bismaleimides and polymers obtained were confirmed by IR spectroscopy and elemental analysis. Characterization of the compounds was undertaken by differential scanning calorimetry, thermooptical analysis, thermogravimetric analysis, viscosity measurements and solubility tests. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation of polymers containing sugar residues

The synthesis of five different polymers containing sugar residues on side chain is described. 1-O-Methacryloyltetra-O-acetyl-D -glucose, 1-O-methacryloyltetra-O-acetyl-D -galactose, and 6-O-methacryloyltetra-O-acetyl-D -glucose were prepared and polymerized. The polymethacrylates obtained were converted into water-soluble polymers by removing the acetyl protective group with sodium methoxide. 6-O-Methacryloyldiisopropylidene-D -galactose was also prepared and polymerized. The isopropylidene protective group was removed by acid hydrolysis. Poly (N-methacryloylglucosamine) was prepared directly by the polymerization of N-methacryloyl-D -glucosamine without the use of any protective group.     

Polysiloxane-supported NAD(P)H model 1-benzyl-1,4-dihydronicotinamide: synthesis and application in the reduction of activated olefins

A new polysiloxane-supported NAD(P)H model, 1-benzyl-1,4-dihydronicotinamide, was designed and synthesized, which can efficiently reduce many activated olefins under mild conditions. The most advantageous features of this new polysiloxane-supported reductant are (i) easy workup and separation of the reaction products and (ii) good potential for recycling use of the reductant, which makes this new polysiloxane-supported NAD(P)H model a promising alternative both in research laboratories and in industrial processes.     

Synthesis and properties of PPE-type conjugated polymers containing tricarbonyl(arene)chromium unit in the main chain

Novel π-conjugated polymers containing (η6-arene)Cr(CO)₃ in the main chain based on poly(p-phenylene-ethynylene) were prepared by the Sonogashira coupling reaction of η6-(1,4-diethynylbenzene)tricarbonylchromium with 1,4-diiodo-2,5-dialkoxybenzenes. The polymers were soluble in common organic solvents and characterized by NMR and FT-IR spectra. The polymers exhibited an absorption maximum at around 390 nm, which showed a red shift of approximately 30 nm compared to that of the model compound. Cyclic voltammogram showed a single reversible oxidation peak derived from the (η6-arene)Cr(CO)₃ unit.     

Synthesis of novel nithiazine analogues containing the 1,4-dihydropyridine structure,and their bioactivity as insecticides

A series of novel nithiazine analogues bearing the 1,4-dihydropyridine structure have been designed and synthesized by reaction of nithiazine, malononitrile or ethyl cyanoacetate, and benzaldehyde. The synthesized compounds were identified by ¹H NMR and IR spectroscopy, and elemental analysis. Preliminary bioassays indicated that most of the compounds had moderate insecticidal activity against Aphis craccivora. The relationship between molecular structure and biological activity is discussed.     

Polymer-supported 1,4-dihydronicotinamide:Synthesis and Application in the Reduction of the Activated Olefins

Three new polymer-supported NAD(P)H models (Ⅰ, Ⅱ, Ⅲ) were designed and synthesized, which can efficiently reduce many activated olefins under mild conditions.1 The most advantageous featureof the three NAD(P)H models is (i) easy work-up and separation of the reaction products and (ii) good potential for recycle use of the NAD(P)H models, which makes the three new polymer-supported NAD(P)H models a promising alternative both in research laboratories and in industrial processes.