7776-34-3Relevant articles and documents
Diastereoselective hydrogenation of pyrazine derivatives: An alternative method of preparing piperazine-(2S)-carboxylic acid
Kukula, Pavel,Prins, Roel
, p. 404 - 411 (2002)
The diastereoselective hydrogenation of a chiral pyrazine derivative was used for the stereoselective preparation of piperazine-2-carboxylic acid, which is an important chiral building block. The study was focused on the diastereoselective hydrogenation with various noble metal catalysts (Pd, Pt, Rh, Ru) on different supports. It was found that intramolecular cyclization of the substrate takes place during the hydrogenation, forming an unsaturated diketopiperazine derivative. This intermediate was further hydrogenated to a mixture of saturated heterocyclic diastereomers. The influence of the reaction conditions (temperature, pressure of hydrogen, and type of solvent) on the diastereoselectivity was also studied. The highest diastereoselectivity (79%) was reached with 10% Pd/C and with water as solvent. The desired molecule of piperazine-2-carboxylic acid was finally obtained by acidic hydrolysis of the diastereomeric diketopiperazine adduct.
Phylogeny-guided isolation of ethyl tumonoate a from the marine cyanobacterium cf. Oscillatoria margaritifera
Engene, Niclas,Choi, Hyukjae,Esquenazi, Eduardo,Byrum, Tara,Villa, Francisco A.,Cao, Zhengyu,Murray, Thomas F.,Dorrestein, Pieter C.,Gerwick, Lena,Gerwick, William H.
, p. 1737 - 1743 (2011)
The evolutionary relationships of cyanobacteria, as inferred by their SSU (16S) rRNA genes, were used as predictors of their potential to produce varied secondary metabolites. The evolutionary relatedness in geographically distant cyanobacterial specimens was then used as a guide for the detection and isolation of new variations of predicted molecules. This phylogeny-guided isolation approach for new secondary metabolites was tested in its capacity to direct the search for specific classes of new natural products from Curacao marine cyanobacteria. As a result, we discovered ethyl tumonoate A (1), a new tumonoic acid derivative with anti-inflammatory activity and inhibitory activity of calcium oscillations in neocortical neurons.
Room temperature depolymerization of lignin using a protic and metal based ionic liquid system: an efficient method of catalytic conversion and value addition
Mehta, Mohit J.,Kulshrestha, Akshay,Sharma, Shweta,Kumar, Arvind
, p. 1240 - 1247 (2021/02/26)
Lignin is one of the most abundant biopolymer which can be utilized to synthesize various chemicalsviaits depolymerization. However, depolymerization of lignin generally occurs under very harsh conditions. Herein, we report the efficient depolymerization of ligninviadissolution in a mixed ionic liquid system: ethyl ammonium nitrate (EAN) + prolinium tetrachloromanganate(ii) [Pro]2[MnCl4] at 35 °C and under atmospheric pressure conditions. The high dissolution of lignin in ethyl ammonium nitrate provided a large number of H-bonding sites leading to the cracking of lignin and subsequent oxidative conversion by [Pro]2[MnCl4]viathe formation of metal-oxo bonding between Mn and lignin molecules. The extracted yield of vanillin was found to be 18-20% on lignin weight basisviaGC-MS analysis. The depolymerization of lignin was confirmed by SEM, FT-IR and PXRD analysis. Since lignin contains UV-absorbing functional groups, the regenerated biomass after the recovery of the depolymerized products was further utilized to synthesize a UV-shielding material. The constructed films from such a material exhibited a high SPF value of 22 and were found to be very effective by limiting the UV degradation of rhodamine B thus making the lignin valorization process economically viable and environmentally sustainable.
Cyclopeptides and polyketides from coral-associated fungus, Aspergillus versicolor LCJ-5-4
Zhuang, Yibin,Teng, Xiancun,Wang, Yi,Liu, Peipei,Wang, Hui,Li, Jing,Li, Guoqiang,Zhu, Weiming
experimental part, p. 7085 - 7089 (2011/10/09)
Three new cyclopentapeptides, versicoloritides A-C (1-3), a new orcinol tetramer, tetraorcinol A (4), and two new lactones, versicolactones A and B (5 and 6) together with three known metabolites, diorcinol, glyantrypine, and cordyol C were isolated from the fermentation broth of the coral-associated fungus Aspergillus versicolor LCJ-5-4. Their structures were elucidated by spectroscopic and chemical methods. The new compounds 1-4 were evaluated for their radical-scavenging activity and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans and cytotoxicity against P388 and Hela cell lines. Compound 4 showed weak radical-scavenging activity against the DPPH radical with an IC50 value of 67 μM.
L-valine and L-proline - solid-state IR-LD spectroscopic study
Chapkanov,Zareva
experimental part, p. 347 - 350 (2011/11/12)
Spectral investigation including IR-characteristic bands assignment of the amino acids zwitterions L-Valine (L-Val) and L-Proline (L-Pro) was carried out by linear-dichroic infrared (IR-LD) spectroscopy of oriented solid sample as a nematic liquid crystal suspension. The obtained experimental IR-LD results (transition moment directions) were compared with known crystal X-ray data for molecules orientation in the unit cells of the studied compounds, confirming the applicability of the used spectral method for structural determination. The influence of the protonation on the IR-spectroscopic patterns of the both amino acids is discussed.
Novel cyclopeptide and unique flavone from Desmos rostrata. Total synthesis of desmorostratone
Nguyen, Ngoc Tuan,Pham, Van Cuong,Litaudon, Marc,Guéritte, Fran?oise,Bodo, Bernard,Nguyen, Van Tuyen,Nguyen, Van Hung
experimental part, p. 7171 - 7176 (2009/12/24)
Two new compounds, a cyclic peptide desmocyclopeptide (1) and a special flavone desmorostratone (2) were isolated from the stem bark of Desmos rostrata, along with two known compounds, desmosdumotins B (3) and C (4). Their structures were established on the basis of the spectral data, including mass spectrometry and 2D NMR. The total synthesis of desmorostratone (2) was performed in order to confirm its structure as well as that of desmosdumotin C (4), which was a tautomeric mixture in the solution. Finally, cytotoxity of these compounds were evaluated. Desmosdumotin C (4) displayed a moderate inhibition activity against KB cell line with an IC50 of 19.2 μM, whereas the other products showed a weak inhibition against the same cell line target.
Synthesis of (ε-13C-,ε-15N)-enriched L-lysine - Establishing schemes for the preparation of all possible 13C and 15N isotopomers of L-lysine, L-ornithine, and L-proline
Siebum, Arjan H. G.,Tsang, Robert K. F.,Van Der Steen, Rob,Raap, Jan,Lugtenburg, Johan
, p. 4391 - 4396 (2007/10/03)
In this paper we describe a simple synthetic strategy that, with the right rational adaptation, gives direct access to any 13C/15N isotopomer of L-glutamate, L-ornithine, L-proline, L-lysine, and L-α, amino adipic acid. This strategy also allows access to nonproteinogenic amino acids like L-citrulline in high yields and optical purity. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Synthesis of specially stable-isotope-labeled L-proline via L-glutamic acid
Cappon, J. J.,Walle, G. A. M. van der,Verdegem, P. J. E.,Raap, J.,Lugtenburg, J.
, p. 517 - 523 (2007/10/02)
(3,4-(13)C2)-L-proline and ((15)N)-L-proline were prepared from the correspondingly labeled L-glutamic acids via a single scheme in high yield and on a gram scale.The synthetic route is based on the ring closure of L-glutamic acid to L-5-oxoproline and the selective reduction of the 5-amide function, without interference with the 2-carboxylate function and the asymmetric center.The selective reduction is effected by first converting the amide into the corresponding thioamide and subsequently reducing the thioamide to the amine using tributyltin hydride, in combination with protection and deprotection steps.In earlier work we described the preparation of L-glutamic acid isotopically labeled at any position or combination of positions starting from simple highly enriched synthons.The synthetic scheme in this publication makes L-proline, (13)C- or (15)N-labeled at any position or combination of positions, easily available.The labeled L-prolines are charcterized by (1)H-, (13)C- and (15)N-NMR and mass spectrometry.
