The isolation and structure determination of cryptomisrine,a novel indolo[3,2-b]quinoline dimeric alkaloid from cryptolepis sanguinolenta

The isolation and structure determination of cryptomisrine, a novel indolo[3,2-b]quinoline dimeric alkaloid obtained from extracts of the roots of the Ghanaian medicinal plant Cryptolepis sanguinolenta is reported. The structure determination was made via a consideration of the spectral data, including uv, ir, nmr, and mass spectra. In particular, one-dimensional proton/carbon nmr, one-dimensional nOe difference nmr, and a series of homonuclear (COSY) and inverse-detected heteronuclear two-dimensional (HMQC, HMBC) experiments were utilized, as well as high resolution FABMS. Cryptomisrine is most unusual in that its two monomeric parts apparently exist in such a C₂ symmetric environment that only one set of proton and carbon nmr resonances are observed. Cryptomisrine is the first example of a dimeric indolo-[3,2-b]quinoline alkaloid to have been isolated from nature.     

Compositional Profiles in Silica-Based Sol-Gel Films Doped with Erbium and Silver, by RBS and ERDA

Photosensitive organic-titania hybrid materials have been prepared from metal alkoxides and various organic ester compounds with double bonds. The refractive index of the film increases with the decrease of the concentration of the organic ester compound, and the highest refractive index of 1.62 is obtained when 2-hydroxymethyl acrylate (HOA) is used as the organic ester and the molar ratio of HOA to Ti is 0.5. The material with the highest refractive index is exposed to femtosecond pulse using the multi-beam laser interference technique. After laser irradiation, the irradiated parts of the material are photopolymerized and periodic structures can be obtained by development of the unirradiated parts. In the case of laser irradiation of 120 J total energy for 5 min, the periodic structure obtained corresponds to 2D photonic crystal structure which is composed of two parts; the material with the highest refractive index and the air.     

A novel microporous copper silicate: Na2Cu2Si4O11.2H2O

The synthesis and structural characterisation of a thermally stable novel three-dimensional microporous copper silicate open-framework are described; the material is capable of undergoing reversible zeolitic water removal without destruction of the framework.     

Biotechnology for production of fuels,chemicals, and materials from biomass

Applied Biochemistry and Biotechnology - Biological systems can convert renewable resources, including lignocellulosic biomass, starch crops, and carbon dioxide, into fuels, chemicals, and...     

The preparation of 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides by the condensation/cyclization of trilithiated acetoacetanilides with lithiated methyl salicylates

Several acetoacetanilides were trilithiated in excess lithium diisopropylamide, and the resulting polylithiated intermediates were regioselectively condensed with lithiated methyl salicylates followed by acid cyclization to substituted 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides (benzopyranone-2-acetamides).     

The reactivity of dimethylaluminum hydride with the aminoarsines Me2AsNMe2, MeAs(NMe2)2, and As(NMe2)3

The reactions of (Me₂AlH)₃ with Me₂AsNMe₂, MeAs(NMe₂)₂, and As(NMe₂)₃ were investigated as a function of time at room temperature and over the temperature range −90 to 24°C by use of ¹H and ¹³C NMR spectroscopy. (Me₂AlH)₃ was found to be very reactive toward the aminoarsines, even at −90°C, and no stable Me₂AlH-aminoarsine adducts were observed. Instead, the initial stages of the reactions involved AS---N bond cleavage with the generation of highly reactive AlN- and AsH-bonded species. The subsequent course of each reaction and the final arsenic-containing product distribution depended upon the original AL:N stoichiometric ratio and the respective aminoarsine. When the Al:N ratio was 1:1, the reactions were straightforward for each aminoarsine. However, in every case, [Me₂AlNMe₂]₂ was the final AlN-containing product. Independent reactions were carried out to verify many of the proposed decomposition pathways that lead to thermodynamically stable products. The results of this study are compared with those of the analogous, previously reported (Me₃Al)₂-aminoarsine systems. Additionally, a new synthetic route to [Me₂AlAsMe₂]₃ has been established from the reaction of (Me₂AlH)₃ with Me₂AsH.     

Preparation of 2,4-diarylquinolines and substituted dihydrobenz-[c]acridines by the condensation of certain c(α),o-dilithiooximes with 2-aminobenzophenones

C(α),O-Dilithiooximes were prepared in an excess of lithium diisopropylamide and condensed with several 2-aminobenzophenones, followed by acid hydrolysis of the oximes to the ketones, which then underwent cyclodehydration and linear dehydration to give substituted quinolines or dihydrobenz[c]acridines.     

Pretreatment of sugarcane bagasse hemicellulose hydrolysate for xylitol production byCandida guilliermondii

Applied Biochemistry and Biotechnology - In order to remove or reduce the concentrations of toxic substances present in the sugarcane bagasse hemicellulose hydrolysate for xyloseto-xylitol...