1738-78-9Relevant articles and documents
p-Toluenesulfonyl Chloride Catalysed Facile Synthesis of O-benzyl-l-amino Acids and Their In Vitro Evaluation
Hegde, Namita,Juvale, Kapil,Prabhakar, Bala
, p. 2129 - 2135 (2020)
Protection and subsequent deprotection of amino acid functional groups play a key role in regioselective peptide synthesis. For protection, carboxylic acid functional groups are often benzylated using p-toluenesulfonic acid catalysed Fischer-Speier esterification reaction. Such reaction involves in situ water formation, which requires subsequent separation by azeotropic distillation for forward shift of equilibrium. To eliminate the need of this corresponding step requiring additional set-up, current study investigated p-toluenesulfonyl chloride as a reasonable alternative catalyst for facile benzylation of selected mono- and di- carboxylic amino acids. Literature reports that p-toluenesulfonyl chloride not only has a better shelf life but also demonstrates better safety in case of accidental systemic absorption over p-toluenesulfonic acid. As the O-benzyl-l-amino acids are often retained without deprotection to constitute the pharmaceutical peptide systems, synthesized compounds were investigated for their biocompatibility using in vitro cytotoxicity assays.
Synthesis of a leopolic acid-inspired tetramic acid with antimicrobial activity against multidrug-resistant bacteria
Mattio, Luce,Musso, Loana,Scaglioni, Leonardo,Pinto, Andrea,Martino, Piera Anna,Dallavalle, Sabrina
, p. 2482 - 2487 (2018/10/04)
The increasing emergence of multidrug-resistant pathogens is one of the biggest threats to human health and food security. The discovery of new antibacterials, and in particular the finding of new scaffolds, is an imperative goal to stay ahead of the evolution of antibiotic resistance. Herein we report the synthesis of a 3-decyltetramic acid analogue of the ureido dipeptide natural antibiotic leopolic acid A. The key step in the synthetic strategy is an intramolecular Lacey-Dieckmann cyclization reaction of a linear precursor to obtain the desired 3-alkyl-substituted tetramic acid core. The synthesized analogue is more effective than the parent leopolic acid A against Gram-positive (Staphylococcus pseudintermedius) and Gram-negative (E. coli) bacteria (MIC 8 μg/mL and 64 μg/mL, respectively). Interestingly, the compound shows a significant activity against Staphylococcus pseudintermedius strains expressing a multidrug-resistant phenotype (average MIC 32 μg/mL on 30 strains tested). These results suggest that this molecule can be considered a promising starting point for the development of a novel class of antibacterial agents active also against resistant strains.
Design, synthesis, and evaluation of cystargolide-based β-lactones as potent proteasome inhibitors
Niroula, Doleshwar,Hallada, Liam P.,Le Chapelain, Camille,Ganegamage, Susantha K.,Dotson, Devon,Rogelj, Snezna,Groll, Michael,Tello-Aburto, Rodolfo
supporting information, p. 962 - 977 (2018/09/04)
The peptidic β-lactone proteasome inhibitors (PIs) cystargolides A and B were used to conduct structure-activity relationship (SAR) studies in order to assess their anticancer potential. A total of 24 different analogs were designed, synthesized and evaluated for proteasome inhibition, for cytotoxicity towards several cancer cell lines, and for their ability to enter intact cells. X-ray crystallographic analysis and subunit selectivity was used to determine the specific subunit binding associated with the structural modification of the β-lactone (P1), peptidic core, (Px and Py), and end-cap (Pz) of our scaffold. The cystargolide derivative 5k, structurally unique at both Py and P1, exhibited the most promising inhibitory activity for the β5 subunit of human proteasomes (IC50 = 3.1 nM) and significant cytotoxicity towards MCF-7 (IC50 = 416 nM), MDA-MB-231 (IC50 = 74 nM) and RPMI 8226 (IC50 = 41 nM) cancer cell lines. Cellular infiltration assays revealed that minor structural modifications have significant effects on the ability of our PIs to inhibit intracellular proteasomes, and we identified 5k as a promising candidate for continued therapeutic studies. Our novel drug lead 5k is a more potent proteasome inhibitor than carfilzomib with mid-to-low nanomolar IC50 measurements and it is cytotoxic against multiple cancer cell lines at levels approaching those of carfilzomib.
One-step preparation of enantiopure l- or d-amino acid benzyl esters avoiding the use of banned solvents
Bolchi, Cristiano,Bavo, Francesco,Pallavicini, Marco
, p. 965 - 974 (2017/04/11)
The enantiomers of amino acid benzyl esters are very important synthetic intermediates. Many of them are currently prepared by treatment with benzyl alcohol and p-toluenesulfonic acid in refluxing benzene or carbon tetrachloride, to azeotropically remove water, and then precipitated as tosylate salt by adding diethyl ether. Here, we report a very efficient preparation of eight l- or d-amino acid benzyl esters (Ala, Phe, Tyr, Phg, Val, Leu, Lys, Ser), in which these highly hazardous solvents are dismissed using cyclohexane as a water azeotroping solvent and ethyl acetate to precipitate the tosylate salt. With some work-up modifications and lower yield, the procedure can be applied also to methionine. Chiral HPLC analysis shows that all the benzyl esters, including the highly racemizable ones such as those of phenylglycine, tyrosine and methionine, are formed enantiomerically pure under these new reaction conditions thus validating the solvents replacement. Contrariwise, toluene cannot be used in place of benzene or carbon tetrachloride because leading to partially or totally racemized amino acid benzyl esters depending on the polar effect of the amino acid α-side chain as expressed by Taft’s substituent constant (σ*).
Mortiamides A-D, Cyclic Heptapeptides from a Novel Mortierella sp. Obtained from Frobisher Bay
Grunwald, Alyssa L.,Berrue, Fabrice,Robertson, Andrew W.,Overy, David P.,Kerr, Russell G.
supporting information, p. 2677 - 2683 (2017/11/06)
Four new cyclic heptapeptides, mortiamides A-D (1-4), were obtained from a novel Mortierella sp. isolate obtained from marine sediment collected from the intertidal zone of Frobisher Bay, Nunavut, Canada. The structures of the compounds were elucidated by NMR spectroscopy and tandem mass spectrometry. The absolute configurations of the amino acids were determined using Marfey's method. Localization of l and d amino acids within each compound was ascertained by retention time comparison of the partial hydrosylate products of each compound to synthesized dipeptide standards using LC-HRMS. Compounds 1-4 did not exhibit any significant antimicrobial or cytotoxic activity.
Esterification of unprotected a-Amino acids in ionic liquids as the reaction media
Biondini, Daniele,Brinchi, Lucia,Germani, Raimondo,Goracci, Laura,Savelli, Gianfranco
experimental part, p. 39 - 44 (2010/08/22)
Ionic liquid 1,3-dimethylimidazolium methanesulfonate was used to prepare a-amino acids benzylic esters from unprotected amino acids and benzyl chloride. Esterification of several amino acids was achieved with satisfactory yields: by-products can be removed by a simple work-up procedure to afford the pure product. The described method is simple, mild, rapid and save.
Synthesis of a peptidomimetic HCMV protease inhibitor library
Xu, Ping,Lin, Wenwei,Zou, Xiaomin
, p. 1017 - 1026 (2007/10/03)
The human cytomegalovirus (HCMV) protease catalyzes the maturational process of the herpes virus assembly protein and plays a key role during the manufacture of viral capsid, and so is an attractive target for potential anti-herpes-virus agents with novel structures and new mechanisms. In this work, a peptidomimetic skeleton was designed and a chemical library containing 32 compounds with different substitutions on the skeleton was prepared by the oxidation of a precursor library, which was constructed from four types of building blocks: 4 carboxylic acids, 2 amines, 2 aldehydes and 2 isocyanides, based on multicomponent condensation following liquid phase strategies. The syntheses of the key building block isocyanides are presented.
Stereocontrolled synthesis of β-lactams via staudinger reaction between phenoxyketenes and chiral imines
Kanwar, Seema,Saluja, Aarti,Khurana,Sharma
, p. 137 - 141 (2007/10/03)
Chiral Schiff bases derived from esters of valine and alanine have been shown to be useful intermediates for the stereoselective synthesis of β-lactams. Staudinger reaction between these compounds and phenoxyketenes, generated in situ, from the corresponding acid chlorides in the presence of triethylamine, provides a mixture of diastereomeric cis-β-lactams. Attempts have been made to separate them using column chromatography and their ratios determined through 1H NMR data.
Effect of stereochemistry on the clearance mechanism of 111in(III)- LABELED D- or L-benzyldiethylenetriaminepentaacetic acid
Deal, Kim A.,Welch, Michael J.
, p. 3986 - 3989 (2007/10/03)
The diethylenetriaminepentaacetic acid (DTPA) derivatives L-Bn-DTPA and D-Bn-DTPA were synthesized and radiolabeled with 111In3+. The uptake and clearance of the compounds were determined through biodistribution and excretion studies in Wistar rats. Both isomers readily cleared from the animal. The D isomer showed relatively high kidney uptake and predominately renal clearance. The L isomer showed substantial kidney and liver uptake with equal biliary and renal clearance. Clearance was also evaluated in TR- Wistar rats, which are defective in the liver canalicular multispecific organic anion transporter (cMOAT) protein. cMOAT mediates hepatobiliary clearance of many organic anions. Both compounds were excreted through the urine in TR- Wistar rats, suggesting that cMOAT is important in the clearance of the compounds from the liver.
Oxygen alkylation of Schiff base derivatives of amino acids
O'Donnell,Cook,Rusterholz
, p. 989 - 993 (2007/10/02)
Higher imine esters 1a-h and 7a-b of amino acids and dipeptides are prepared in 68-91% yield by saponification of the benzophenone Schiff base methyl esters 3a-d and 6 using phase-transfer techniques followed by O-alkylation with an alkyl halide. The procedure occurs with retention of configuration at the α-carbon except with phenylglycine derivatives.
