16881-32-6Relevant articles and documents
Carbamate Synthesis Using a Shelf-Stable and Renewable C1 Reactant
Dobi, Zoltán,Reddy, B. Narendraprasad,Renders, Evelien,Van Raemdonck, Laurent,Mensch, Carl,De Smet, Gilles,Chen, Chen,Bheeter, Charles,Sergeyev, Sergey,Herrebout, Wouter A.,Maes, Bert U. W.
, p. 3103 - 3114 (2019/06/24)
4-Propylcatechol carbonate is a shelf-stable, renewable C1 reactant. It is easily prepared from renewable 4-propylcatechol (derived from wood) and dimethyl carbonate (derived from CO2) using a reactive distillation system. In this work, the 4-propylcatechol carbonate is used for the two-step synthesis of carbamates under mild reaction conditions. In the first step, 4-propylcatechol carbonate is treated with an alcohol at 50–80 °C in the presence of a Lewis acid catalyst, such as Zn(OAc)2?2 H2O. With liquid alcohols, no solvent is used and with solid alcohols 2-methyltetrahydrofuran is used as solvent. In the second step, the alkyl 2-hydroxy-propylphenyl carbonate intermediates obtained react with amines at room temperature in 2-methyltetrahydrofuran, forming the target carbamates and the byproduct 4-propylcatechol, which can be recycled into a carbonate reactant.
TRANSESTERIFICATION REACTION BY MEANS OF IRON CATALYST
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Paragraph 0134; 0135; 0142; 0143, (2017/10/10)
Provided is a catalyst for transesterification reactions, which contains an iron salen complex. Also provided is a method for producing an ester compound, which is characterized by carrying out a transesterification reaction between a starting material ester and a starting material alcohol with use of the catalyst.
Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: Tailored gold-based anticancer peptidomimetics
Negom Kouodom, Morelle,Ronconi, Luca,Celegato, Marta,Nardon, Chiara,Marchiò, Luciano,Dou, Q. Ping,Aldinucci, Donatella,Formaggio, Fernando,Fregona, Dolores
supporting information; scheme or table, p. 2212 - 2226 (2012/05/05)
Complexes [AuIIIX2(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [AuIIIBr2(dtc-Sar-Aib-O(t- Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC50 values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.
ZINC CLUSTER
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Page/Page column 4, (2012/07/14)
Disclosed is a novel zinc cluster compound represented by general formula (1): Zn4O (OCOR)6 (RCOOH)n, wherein R represents an alkyl group which has 1 to 4 carbon atoms and may be substituted with a halogen atom, and n repr
Synthesis and self-association properties of flexible guanidiniocarbonylpyrrole-carboxylate zwitterions in DMSO: Intra- versus intermolecular ion pairing
Schmuck, Carsten,Rehm, Thomas,Geiger, Lars,Schaefer, Mathias
, p. 6162 - 6170 (2008/02/10)
(Chemical Equation Presented) We have synthesized a new class of flexible zwitterions 6a-e, in which a carboxylate is linked via an alkyl chain with variable length (one to five methylene groups) to a guanidiniocarbonylpyrrole cation. The self-association properties of these zwitterions were determined by NMR dilution studies in DMSO and by ESI-MS experiments. The stability and hence also the size of the aggregates formed via self-assembly is critically dependent on the length and therefore flexibility of the spacer. Whereas the smallest zwitterion 6a forms large aggregates already at low concentrations, the more flexible zwitterions only form small oligomers (6b) or dimers (6c-e) at much larger concentrations. The differences between the five zwitterions can be explained based on the different extent of intramolecular ion pairing within the monomers. Any intramolecular ion pairing, which becomes possible with increasing linker length, stabilizes the monomer and therefore destabilizes any oligomer.
Preferred conformations of peptides containing tert-leucine, a sterically demanding, lipophilic α-amino acid with a quaternary side-chain C β atom
Formaggio, Fernando
, p. 2395 - 2404 (2007/10/03)
Terminally protected homopeptides of tert-leucine, from the dimer to the bexamer, co-oligopeptides of tert-leucine in combination with α-aminoisobutyric acid or glycine residues up to the hexamer level, and simple dipeptides representing known scaffolds for catalysts in asymmetric organic reactions were prepared by solution methods and fully characterized. The results of conformation analysis, performed by use of FT-IR absorption, NMR, CD, and X-ray diffraction techniques, indicate that this Hydrophobic α-amino acid with tetrasubstitution at the Cβ atom is structurally versatile. We show that it prefers extended or semiextended conformations, but can also be accommodated in folded structures, pro vided that these are biased by the presence of helicogenic residues. The current large-scale production of Tle, combined with its conformational preferences unravelled in this work, should make this bulky, hydrophobic, C α-trisubstituted α-amino acid a regular building block of any strategy seeking to tailor peptides with improved catalytic and pharmacological properties.
Preparation and Characterization of [5-13C]-(2S,4R)-Leucine and [4-13C]-(2S,3S)-Valine - Establishing Synthetic Schemes to Prepare Any Site-Directed Isotopomer of L-Leucine, L-Isoleucine and L-Valine
Siebum, Arjan H. G.,Woo, Wei Sein,Lugtenburg, Johan
, p. 4664 - 4678 (2007/10/03)
In this paper a chemo-enzymatic method has been developed that gives access to any isotopomer of the essential amino acids isoleucine and valine. The method gives the correct introduction of the second chiral center in (2S,3S)-isoleucine and allows for discrimination between the two prochiral methyl groups in valine as shown by the preparation of (2S,3S)-[4- 13C] valine. For the preparation of (2S)-leucine in any isotopomeric form, the O'Donnell method to prepare optically active amino acids has been used. The protected glycine scaffold used in this method has been prepared by a strategy that allows access to any isotopomeric form. The preparation of [5-13C]-(2S,4R)-leucine shows that the O'Donnell method in combination with the Evans method to obtain chiral 2-methylpropyl iodide leads to a good discrimination between the two prochiral methyl groups. The O'Donnell strategy for the preparation of α-amino acids is preferred over other methods since the reaction conditions are mild, the chiral auxiliary can be easily recovered and the optically active product can be easily separated. For the preparation of isotopically enriched valine and isoleucine the O'Donnell method is not suitable, because the alkyl substituents involved have a secondary halide substituent which is sterically too hindered to give an effective reaction with the protected glycine. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
The use of cellulose (chromatography paper) as a cheap, versatile and non-covalent support for organic molecules during multi-step synthesis
Shanahan, Stephen E.,Byrne, Douglas D.,Inglis, Graham G. A.,Alam, Mahbub,Macdonald, Simon J. F.
, p. 2554 - 2555 (2007/10/03)
Cellulose chromatography paper provides a novel non-covalent support for synthesis and in-situ purification of multi-dimensional arrays.
Liposidomycins - Synthetic studies towards the ribosyldiazepanone moiety
Gravier-Pelletier, Christine,Milla, Maria,Merrer, Yves Le,Depezay, Jean-Claude
, p. 3089 - 3096 (2007/10/03)
A synthesis of the enantiopure 2-ribosyl-1,4-diazepan-3-one core of liposidomycins, a class of complex lipid nucleoside antibiotics, according to a flexible asymmetric synthesis strategy is described. It involves two building blocks, an enantiopure α-azido-β,γ-epoxybutanol readily available from L-ascorbic acid, and an α-ribosylamino acid obtained from D-ribose. Subsequent cyclization by regiospecific nucleophilic opening of the epoxide by the amino acid followed by peptidic coupling affords the target ribosyl diazepanone.
Building Units for N-Backbone Cyclic Peptides. 3. Synthesis of Protected Nα-(ω-Aminoalkyl)amino Acids and Nα-(ω-Carboxyalkyl)amino Acids
Muller, Dan,Zeltser, Irena,Bitan, Gal,Gilon, Chaim
, p. 411 - 416 (2007/10/03)
An improved synthesis of a family of amino acids that contain ω-aminoalkyl groups and of a new family containing ω-carboxyalkyl groups linked to the α-amine is described. The synthesis was performed by alkylation of suitably monoprotected alkylenediamines and protected ω-amino acids with triflates of α-hydroxy acid esters. The reaction proceeded with inversion of configuration yielding optically pure products. The Nα-(ω-aminoalkyl)amino acids and Nα-(ω-carboxyalkyl)amino acids were orthogonally protected to allow their incorporation into peptides by solid-phase peptide synthesis (SPPS) methodology.
