- Sequential One-Pot Synthesis of Dipeptides through the Transient Formation of CDI-N-Protected α-Aminoesters
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The synthesis of dipeptides through a sequential one-pot procedure from commercially available protected amino acids is described. The transformation relies on the use of in situ generated transiently CDI-protected α-amino esters (CDI, e.g. N,N′-carbonyldiimidazole). In addition of being a highly atom-economical process, the couplings take place under very mild and neutral conditions without adding a base to the reaction medium. This protocol provides a concise and less costly route to dipeptide derivatives (12 examples, up to 87% yield) and is compatible with commonly used N-urethane protecting groups. Moreover, no epimerization was detected even when sensitive Boc-Cys(Bn)?OH was used. (Figure presented.).
- de Figueiredo, Renata Marcia,Suppo, Jean-Simon,Midrier, Camille,Campagne, Jean-Marc
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Read Online
- Controlling Syneresis of Hydrogels Using Organic Salts
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Supramolecular hydrogels can spontaneously undergo syneresis through fibre–fibre interactions and expel significant amounts of water upon aging. In this process, the hydrophobicity of fibres which regulates the 3D-rearrangement of the self-assembled struc
- Panja, Santanu,Dietrich, Bart,Adams, Dave J.
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- Optimization and anti-cancer properties of fluoromethylketones as covalent inhibitors for ubiquitin C-terminal hydrolase L1
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The deubiquitinating enzyme (DUB) UCHL1 is implicated in various disease states including neurodegenerative disease and cancer. However, there is a lack of quality probe molecules to gain a better understanding on UCHL1 biology. To this end a study was carried out to fully characterize and optimize the irreversible covalent UCHL1 inhibitor VAEFMK. Structure-activity relationship studies identified modifications to improve activity versus the target and a full cellular characterization was carried out for the first time with this scaffold. The studies produced a new inhibitor, 34, with an IC50 value of 7.7 μM against UCHL1 and no observable activity versus the closest related DUB UCHL3. The molecule was also capable of selectively inhibiting UCHL1 in cells and did not demonstrate any discernible off-target toxicity. Finally, the molecule was used for initial probe studies to assess the role of UCHL1 role in proliferation of myeloma cells and migration behavior in small cell lung cancer cells making 34 a new tool to be used in the biological evaluation of UCHL1.
- Chen, Hao,Das, Chittaranjan,Flaherty, Daniel P.,Galardy, Paul J.,Hewitt, Chad S.,Hussain, Sajjad,Imhoff, Ryan D.,Krabill, Aaron D.,Muli, Christine S.,Wendt, Michael K.
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supporting information
(2021/05/31)
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- Effect of Stereochemistry on Chirality and Gelation Properties of Supramolecular Self-Assemblies
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Although chiral nanostructures have been fabricated at various structural levels, the transfer and amplification of chirality from molecules to supramolecular self-assemblies are still puzzling, especially for heterochiral molecules. Herein, four series o
- Qin, Minggao,Zhang, Yaqian,Xing, Chao,Yang, Li,Zhao, Changli,Dou, Xiaoqiu,Feng, Chuanliang
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p. 3119 - 3129
(2021/01/20)
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- Cobalt-Catalyzed C(sp2)-H Carbonylation of Amino Acids Using Picolinamide as a Traceless Directing Group
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Herein we report an efficient protocol for the C(sp2)-H carbonylation of amino acid derivatives based on an inexpensive cobalt(II) salt catalyst. Carbonylation was accomplished using picolinamide as a traceless directing group, CO (1 atm) as the carbonyl
- Lukasevics, Lukass,Cizikovs, Aleksandrs,Grigorjeva, Liene
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supporting information
p. 2748 - 2753
(2021/04/12)
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- Chiral Overpass Induction in Dynamic Helical Polymers Bearing Pendant Groups with Two Chiral Centers
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The dynamic behavior of helical polymers bearing pendant groups with two chiral centers was studied. Controlled conformational changes at the chiral units placed either closer to or further away from the main chain promote different helical structures. Al
- Freire, Félix,Qui?oá, Emilio,Riguera, Ricardo,Suárez-Picado, Esteban
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supporting information
p. 4537 - 4543
(2020/02/04)
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- In vitro and in silico determination of glutaminyl cyclase inhibitors
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Alzheimer's disease (AD) is the most common form of neurodegenerative disease currently. It is widely accepted that AD is characterized by the self-assembly of amyloid beta (Aβ) peptides. The human glutaminyl cyclase (hQC) enzyme is characterized by assoc
- Tran, Phuong-Thao,Hoang, Van-Hai,Lee, Jeewoo,Hien, Tran Thi Thu,Tung, Nguyen Thanh,Ngo, Son Tung
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p. 29619 - 29627
(2019/10/02)
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- Substrate-directed lewis-acid catalysis for peptide synthesis
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A Lewis-acid-catalyzed method for the substrate-directed formation of peptide bonds has been developed, and this powerful approach is utilized for the new "remote" activation of carboxyl groups under solvent-free conditions. The presented method has the following advantages: (1) the high-yielding peptide synthesis uses a tantalum catalyst for any amino acids; (2) the reaction proceeds without any racemization; (3) the new substrate-directed chemical ligation using the titanium catalyst is applicable to convergent peptide synthesis. These advantages overcome some of the unresolved problems in classical peptide synthesis.
- Muramatsu, Wataru,Hattori, Tomohiro,Yamamoto, Hisashi
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supporting information
p. 12288 - 12295
(2019/08/20)
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- Peptide Bond Formation via Nα-Protected Diacyldiselenides
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Abstract: A simple, straightforward, for the peptide bond formation employing corresponding carboxylic acids and amines derived from amino acids via Nα-protected diacyldiselenide is delineated. The key step of the synthesis is the in situ gener
- Vathsala,Roopesh Kumar,Sagar,Mahesh,Venkata Ramana,Sureshbabu, Vommina V.
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p. 653 - 658
(2018/04/26)
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- REDOX DEHYDRATION COUPLING CATALYSTS AND METHODS RELATED THERETO
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This disclosure relates to synthetic coupling methods using catalytic molecules. In certain embodiments, the catalytic molecules comprise heterocyclic thiolamide, S-acylthiosalicylamide, disulfide, selenium containing heterocycle, diselenide compound, ditelluride compound or tellurium containing heterocycle. Catalytic molecules disclosed herein are useful as catalysts in the transformation of hydroxy group containing compounds to amides, esters, ketones, and other carbon to heteroatom or carbon to carbon transformations.
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- 9-Silafluorenyl Dichlorides as Chemically Ligating Coupling Agents and Their Application in Peptide Synthesis
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A fundamentally simple, mild, and practical procedure for peptide bond formation is reported that employs a stoichiometric amount of easy-to-access 9-silafluorenyl dichlorides as the coupling agent. Without initial preactivation or elaboration of the carboxylic acid or amine termini of the amino acids, the developed reagent is proposed to act through an unprecedented chemical ligation mechanism, bringing the two coupling partners together before being subsequently eliminated. The desired amides or peptide bonds are thus furnished in good yields and with low to no epimerization.
- Aspin, Samuel J.,Taillemaud, Sylvain,Cyr, Patrick,Charette, André B.
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supporting information
p. 13833 - 13837
(2016/10/26)
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- SMALL MOLECULE MODULATORS OF PCSK9 AND METHODS OF USE THEREOF
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A compound of Formula (I): or a pharmaceutically acceptable salt, hydrate, solvate, or racemic mixture or stereoisomer thereof, and methods for preventing or treating an LDL-cholesterol-related disease or disorder using such compound(s), and kits and comp
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Paragraph 0344
(2016/02/22)
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- An efficient mechanochemical synthesis of amides and dipeptides using 2,4,6-trichloro-1,3,5-triazine and PPh3
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A rapid, facile, and efficient mechanochemical synthesis of amides from carboxylic acids has been developed through an in situ acid activation with 2,4,6-trichloro-1,3,5-triazine and a catalytic amount of PPh3. Under room temperature solvent-drop grinding of the reactants in the presence of an inorganic base, a variety of carboxylic acids including aromatic acids, aliphatic acids, and N-protected α-amino acids undergo amidation to afford amides in moderate to excellent yields. The method is also compatible with Fmoc, Cbz, and Boc protecting groups which yields protected optically active dipeptides without detectable racemization.
- Duangkamol, Chuthamat,Jaita, Subin,Wangngae, Sirilak,Phakhodee, Wong,Pattarawarapan, Mookda
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p. 52624 - 52628
(2015/06/25)
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- Macrocyclization of Peptide Side Chains by the Ugi Reaction: Achieving Peptide Folding and Exocyclic N-Functionalization in One Shot
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The cyclization of peptide side chains has been traditionally used to either induce or stabilize secondary structures (β-strands, helices, reverse turns) in short peptide sequences. So far, classic peptide coupling, nucleophilic substitution, olefin metat
- Vasco, Aldrin V.,Pérez, Carlos S.,Morales, Fidel E.,Garay, Hilda E.,Vasilev, Dimitar,Gavín, José A.,Wessjohann, Ludger A.,Rivera, Daniel G.
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p. 6697 - 6707
(2015/10/06)
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- A novel aromatic carbocation-based coupling reagent for esterification and amidation reactions
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A novel tropylium-based coupling reagent has been developed to facilitate the synthesis of a series of esters, amides, lactones and peptides under mild reaction conditions. Remarkably, this reagent can be used in catalytic amounts in conjunction with a sacrificial reagent, offering a new and efficient method for nucleophilic coupling reactions of carboxylic acids.
- Nguyen, Thanh V.,Lyons, Demelza J.M.
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supporting information
p. 3131 - 3134
(2015/06/17)
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- Borinic acid catalysed peptide synthesis
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The catalytic synthesis of peptides is a major challenge in the modern organic chemistry hindered by the well-established use of stoichiometric coupling reagents. Herein, we describe for the first time that borinic acid is able to catalyse this reaction under mild conditions with an improved activity compared to our recently developed thiophene-based boronic acid. This catalyst is particularly efficient for peptide bond synthesis affording dipeptides in good yields without detectable racemization.
- El Dine, Tharwat Mohy,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 16084 - 16087
(2015/11/10)
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- Amino Acid Chirality and Ferrocene Conformation Guided Self-Assembly and Gelation of Ferrocene-Peptide Conjugates
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The self-assembly and gelation behavior of a series of mono- and disubstituted ferrocene (Fc)-peptide conjugates as a function of ferrocene conformation and amino acid chirality are described. The results reveal that ferrocene-peptide conjugates self-asse
- Adhikari, Bimalendu,Singh, Charanpreet,Shah, Afzal,Lough, Alan J.,Raatz, Heinz-Bernhard
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supporting information
p. 11560 - 11572
(2015/08/03)
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- Synthesis and conformation studies of rubiyunnanin B analogs
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Five new analogs 4-8 of rubiyunnanin B (1), mainly modified on the tetrapeptide subunit, were synthesized. These agents 4-8 were substituted d-Ala-l-Ala-l-Tyr(OMe)-l-Ala, d-Ala-l-Ala-l-Phe-l-Ala, d-Ala-l-Ala-l-Try-l-Ala, d-Ala-l-Ala-l-Pro-l-Ala, and d-Ala-l-Ala-l-Ala for the d-Ala-l-Ala-l-N-Me-Tyr(OMe)-l-Ala tetrapeptide subunit. Unlike the natural product, the synthetic agents 4-8 adopt only a single solution conformation, and the central peptide bond in the cyclodityrosine subunit of compounds 4-8 adopt trans stereochemistry. Cytotoxic activities of analogs 4-8 against three human cancer cell lines including A549, BGC-823, and HeLa were evaluated and all the five synthesized peptides exhibited no effects against the test cell lines. These compounds were also evaluated for their antiinsulin resistance and insulin sensitizing activities and none of them showed activity in these assays.
- Liu, Na-Na,Zhao, Si-Meng,Zhao, Jing-Feng,Zeng, Guang-Zhi,Tan, Ning-Hua,Liu, Jian-Ping
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p. 6630 - 6640
(2015/03/30)
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- Deprotection/reprotection of the amino group in α-amino acids and peptides. A one-pot procedure in [Bmim][BF4] ionic liquid
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This paper presents an efficient one-pot protocol for the sequential deprotection/reprotection of the α-amino group in α-amino acid and dipeptide methyl esters. [Bmim][BF4] is used as the solvent in the entire process. In particular, the use of the ionic liquid allows for rapid and clean removal of the 4-nitrobenzenesulfonyl (nosyl) group and for facile subsequent tert-butyloxycarbonylation of the free α-amino function under very mild conditions. N-Boc-α-amino acid as well as peptide derivatives are isolated in excellent yields, and do not require any further purification. Absolute configurations of the precursors are totally preserved during the process.
- Di Gioia,Barattucci,Bonaccorsi,Leggio,Minuti,Romio,Temperini,Siciliano
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p. 2678 - 2686
(2014/01/06)
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- Furan-based locked Z -vinylogous γ-amino acid stabilizing protein α-turn in water-soluble cyclic α3γ tetrapeptides
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Described here is the design, synthesis, and conformational analysis of cyclic tetrapeptides (CTPs) with α3γ architecture containing a furan-based locked Z-vinylogous amino acid (Vaa). This unnatural amino acid locks into a γ-turn that induces
- Krishna, Yarkali,Sharma, Shrikant,Ampapathi, Ravi S.,Koley, Dipankar
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supporting information
p. 2084 - 2087
(2014/05/06)
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- Synthesis and conformational characterization of diketopiperazines bearing a benzyl moiety
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Diketopiperazines bearing a benzyl moiety with different para-substituents were synthesized and analyzed by 1HNMR spectroscopy. All of these diketopiperazines were found to adopt a folded conformation according to the upfield chemical shift of the cis-proton (cis to the benzyl moiety) due to a shielding effect in the 1HNMR spectra. An intramolecular CH-π interaction appears to be an important factor for the folded conformation due to the effects of para-substituents on the benzyl group.
- Nakao, Michiyasu,Toriuchi, Yuriko,Fukayama, Shintaro,Sano, Shigeki
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p. 340 - 342
(2014/03/21)
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- Thioacetic acid/NaSH-mediated synthesis of N -protected amino thioacids and their utility in peptide synthesis
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Thioacids are recently gaining momentum due to their versatile reactivity. The reactivity of thioacids has been widely explored in the selective amide/peptide bond formation. Thioacids are generally synthesized from the reaction between activated carboxylic acids such as acid chlorides, active esters, etc., and Na2S, H2S, or NaSH. We sought to investigate whether the versatile reactivity of the thioacids can be tuned for the conversion of carboxylic acids into corresponding thioacids in the presence of NaSH. Herein, we report that thioacetic acid- and NaSH-mediated synthesis of N-protected amino thioacids from the corresponding N-protected amino acids, oxidative dimerization of thioacids, crystal conformations of thioacid oxidative dimers, and the utility of thioacids and oxidative dimers in peptide synthesis. Our results suggest that peptides can be synthesized without using standard coupling agents.
- Mali, Sachitanand M.,Gopi, Hosahudya N.
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p. 2377 - 2383
(2014/04/17)
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- Inverse peptide synthesis via activated α-aminoesters
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A mild, practical, and simple procedure for peptide-bond formation is reported. Instead of activation of the carboxylic acid functionality, the reaction involves an unprecedented use of activated α-aminoesters. The method provides a straightforward entry to dipeptides and was effective when a sensitive cysteine residue was used, as no epimerization was detected in this case. The applicability of this method to iterative peptide synthesis was illustrated by the synthesis of a model tetrapeptide in the challenging reverse N→C direction. How to advance by going into reverse: In a mild and practical procedure for peptide-bond formation, free α-aminoesters were activated by treatment with N,N′-carbonyldiimidazole, instead of activating the carboxylic acid functionality (see scheme). The method provided a straightforward route to dipeptides, and its applicability to iterative peptide synthesis was illustrated by the synthesis of a tetrapeptide in the challenging reverse N→C direction.
- Suppo, Jean-Simon,Subra, Gilles,Berges, Matthieu,Marcia De Figueiredo, Renata,Campagne, Jean-Marc
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supporting information
p. 5389 - 5393
(2014/06/09)
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- Phosphorus oxychloride as an efficient coupling reagent for the synthesis of esters, amides and peptides under mild conditions
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A mild method is described for the conversion of carboxylic acids into esters, amides, as well as peptides without racemization through carboxyl activation by the reagent combination of POCl3 and DMAP. Long chain alcohols could be converted to the corresponding ester in good yields. 31P NMR spectrum was used to detect phosphorus-containing intermediates in ongoing reactions directly, and a possible mechanism has been proposed based on these results. The Royal Society of Chemistry 2013.
- Chen, Hu,Xu, Xunfu,Liu, Liu,Tang, Guo,Zhao, Yufen
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p. 16247 - 16250
(2013/09/23)
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- Antimicrobial toxicity studies of ionic liquids leading to a 'hit' MRSA selective antibacterial imidazolium salt
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Imidazolium salts can be classed as surfactants, detergents, ionic liquids, reagents, catalysts or solvents. A study of the toxicity and ecotoxicity of these salts yields valuable information for their use as pharmaceuticals as well as impact on the environment. Our approach to screen a series of chiral imidazolium salts for toxicity to bacteria and fungi, including clinical pathogen strains, has led to the identification of a 'hit' MRSA selective antimicrobial compound. Preliminary structure-activity-relationship (SAR) information (required position of l-phenylalanine and l-valine group) is also elucidated within this first generation of compounds. Conversely, most of the imidazolium salts were nontoxic (IC95 > 2 mM) to the 12 fungi strains and 8 bacteria strains screened, and we propose that they are suitable candidates for 'green chemistry' applications. Ecotoxicity studies (Biodegradation ISO 14593 'CO2 Headspace Test') of two bromide ionic liquids containing l-phenylalanine residues indicate that these ionic liquids passed the test (>60% in 28 days) and classed as readily biodegradable.
- Coleman, Deborah,Spulak, Marcel,Garcia, M. Teresa,Gathergood, Nicholas
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body text
p. 1350 - 1356
(2012/06/16)
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- Selective esterifications of primary alcohols in a water-containing solvent
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Oxyma and an oxyma derivative, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl 2-cyano-2-(hydroxyimino)acetate (5b), displayed a remarkable effect on selective esterifications of primary alcohols. A wide range of carboxylic acids could be esterified with primary alcohols by using EDCI, NaHCO3, and Oxyma or Oxyma derivative 5b in 5% H2O-CH3CN. Oxyma derivative 5b is particularly useful, since it could be removed after the reaction via a simple basic or an acidic aqueous workup procedure.
- Wang, Yong,Aleiwi, Bilal A.,Wang, Qinghui,Kurosu, Michio
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p. 4910 - 4913,4
(2012/12/12)
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- Selective esterifications of primary alcohols in a water-containing solvent
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Oxyma and an oxyma derivative, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl 2-cyano-2-(hydroxyimino)acetate (5b), displayed a remarkable effect on selective esterifications of primary alcohols. A wide range of carboxylic acids could be esterified with primary alcohols by using EDCI, NaHCO3, and Oxyma or Oxyma derivative 5b in 5% H2O-CH3CN. Oxyma derivative 5b is particularly useful, since it could be removed after the reaction via a simple basic or an acidic aqueous workup procedure.
- Wang, Yong,Aleiwi, Bilal A.,Wang, Qinghui,Kurosu, Michio
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p. 4910 - 4913
(2013/01/15)
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- Amino acids as building blocks for the synthesis of substituted 1,2,4-triazoles
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We report on the synthesis of 1,2,4-triazoles substituted with 2 or 3 amino acid side chains, using silver benzoate as a key reagent for the cyclization step. A complete study of the optical purity retention during the synthetic process leading to these c
- Bibian, Mathieu,Martinez, Jean,Fehrentz, Jean-Alain
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scheme or table
p. 7042 - 7049
(2011/10/04)
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- Biomimetic peptide bond formation in water with aminoacyl phosphate esters
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Aminoacyl phosphates, biomimetic analogues of aminoacyl adenylates, react efficiently with amino acid esters to form dipeptides with retention of stereochemical integrity. The reactions are selective and occur readily in the presence of nucleophiles other than amino groups on their side chains. Aminoacyl phosphate esters that lack an amino-protecting group are also suitable for peptide bond formation, leading to a simplified overall process.
- Dhiman, Raj S.,Opinska, Liliana Guevara,Kluger, Ronald
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supporting information; experimental part
p. 5645 - 5647
(2011/09/15)
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- Solvent-free synthesis of peptides
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Chamical Equation Presentation A crush on sweetness! The coupling of a urethane-protected N-carboxyanhydride of an amino acid with another amino acid derivative under ball-milling conditions gives a protected dipeptide in very high yield (see scheme; PG: protecting group). The reaction takes place in the solid state. The synthesis was applied to the preparation of a tri peptide and the sweetener aspartame, without any organic solvent or purification.
- Declerck, Valerie,Nun, Pierrick,Martinez, Jean,Lamaty, Frederic
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supporting information; experimental part
p. 9318 - 9321
(2010/03/24)
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- Tryptophan-containing dipeptide derivatives as potent PPARγ antagonists: Design, synthesis, biological evaluation, and molecular modeling
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The discovery of peroxisome proliferator-activated receptor γ (PPARγ) antagonists (also termed "selective PPARγ modulators, SPPARγM") is now of a great interest in the treatment of diabetes and obesity. The structure of compound 1a (G3335, Fig. 1), a novel class of PPARγ antagonist, is entirely different from that of other reported PPARγ antagonists. A series of 35 novel analogues (1b-l, 9a-d, 13a-t) were designed, synthesized and evaluated against the agonistic effects exerted by rosiglitazone. These results indicated that most functional groups of 1a were conserved, and six new compounds (1b, 1c, and 9a-d) exhibited strong PPARγ antagonistic activities (IC50 values of 5.2-25.8 μM) against 10 μM rosiglitazone in the promotion of the PPARγ-LBD-CBP (ligand-binding domain and cAMP-response-element binding protein) interaction as investigated by yeast two-hybrid technology based assay. Molecular modeling studies for compounds 1a-d, 1h, 9c-d, and 13a were also presented.
- Deng, Guanghui,Liu, Zhiguo,Ye, Fei,Luo, Xiaomin,Zhu, Weiliang,Shen, Xu,Liu, Hong,Jiang, Hualiang
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experimental part
p. 2699 - 2716
(2009/04/11)
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- Synthesis and pharmacological investigation of segetalin C as a novel antifungal and cytotoxic agent
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In present study, a natural phenylalanine-rich cycloheptapeptide segetalin C (compound VIII) was synthesized by coupling and cyclization of peptide units Boc-gly-L-leu-L-his-OH and L-Phe-L-ala-L-phe-L-pro-OMe and examined for different bioactivities. The
- Dahiya, Rajiv,Kaur, Komalpreet
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- Synthesis and properties of N-substituted saccharin derivatives
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Four different routes for the synthesis of saccharin containing peptids were studied. While reactions between saccharin sodium and α-halogeno acids were limited to two examples, reactions of sulfobenzoic anhydride (4) or saccharin-N-carboxylate (6) with amino acid esters yielded the ring opened products 5 and 7. Finally, we found, that the reaction between the benzoxathiol derivative 8 and amino acid derivatives represents a versatile route to the peptidic compounds 9 and 11. Hydrolysis and hydrogenolysis were studied, and by combination of the different routes the "saccharin tripeptides" 18 were obtained. Structures and stereochemistry were elucidated by spectroscopic and chromatographic methods. Selected compounds were tested as sweeteners of as inhibitors of elastase, but no exiting results were found.
- Soubh,Besch,Otto, Hans-Hartwig
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p. 384 - 392
(2007/10/03)
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- METHOD FOR STORING QUATERNARY AMMONIUM SALT
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A method of improving the stability of a quaternary ammonium salt and a method of efficiently preparing the quaternary ammonium salt having improved stability.
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- A facile synthesis of amides from 9-fluorenylmethyl carbamates and acid derivatives
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A mild and convenient one-pot procedure for the synthesis of amides from 9-fluorenylmethyl carbamates and acids using potassium fluoride, triethylamine and various coupling reagents in DMF at room temperature is described. The scope of this procedure was also tested in the coupling of a variety of 9-fluorenylmethyloxycarbonyl-protected amines with active moieties such as anhydrides, acyl imidazolides, activated esters, tosyl chlorides, and acyl halides.
- Li, Wen-Ren,Chou, Hsueh-Hsuan
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- A new approach to the synthesis of dipeptides with unnatural amino acids using organozinc chemistry
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Dipeptides which incorporate an iodoalanine unit at either the N- or C-terminus can be converted into the corresponding organozinc reagents upon treatment with activated zinc.The C-terminal dipeptide organozinc reagents undergo palladium-catalysed reaction with electrophiles to give dipeptides incorporating non-proteinogenic amino acids without loss of stereochemical purity.The N-terminal organozinc reagents are less synthetically useful.
- Dunn, Michael J.,Gomez, Sylvie,Jackson, Richard F. W.
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p. 1639 - 1640
(2007/10/02)
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- Intramolecular ligation of carbonyl oxygen to central zinc in synthetic oligopeptide-linked zinc-porphyrins
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Oligopeptide-linked zinc-porphyrins were prepared (oligopeptide = -Phe(m)-Ala(n)-OMe and porphyrin = 5,15-diaryl-2,3,7,8,12,13,17,18-octaethylporphyrin). 1H NMR, IR, visible, and CD spectra of the synthetic molecule in a chlorinated methane (CDCl3 or CH2Cl2) showed that the carbonyl oxygen of the N-terminal amino acid of the linked peptide should ligate the central zine metal in the molecule as the axial ligand to form a pentacoordinated zinc-porphyrin. The coordination of the zinc with the peptide framework changed the optical and electrical properties, indicating that such ligation might control the reactivity in biological metallotetrapyrrole-protein systems as well as the coordination to the peptide residue.
- Tamiaki,Kiyomori,Maruyama
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p. 2478 - 2486
(2007/10/02)
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- Amide bond formation via pentafluorothiophenyl active esters
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A number of pentafluorothiophenyl (PFTP) esters were shown to be useful acyl donors for amide bond formation, being non-polar, stable to chromatography and extended storage, but sufficiently active for use with relatively unreactive acyl groups. In partic
- Davis, Anthony P.,Walsh, John J.
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p. 4865 - 4868
(2007/10/02)
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- Design of helical peptides: Solution conformation of Boc-Gly-ΔZPhe-Leu-ΔZPhe-Ala-NHMe and Boc-Val-ΔZPhe-Phe-Ala-Leu-Ala-ΔZPhe-Leu-OMe
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Two model peptides have been synthesized, a pentapeptide 1 (Boc-Gly-ΔZPhe-Leu-ΔZPhe-Ala-NHMe) and an octapeptide 2 (Boc-Val-ΔZPhe-Phe-Ala-Δ ZPhe-Phe-Ala-Leu-Ala-gDZPhe-Leu-OMe). The conformations have
- Bharadwaj,Jaswal,Chauhan
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p. 2691 - 2708
(2007/10/02)
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- Transesterifications with 1,8-Diazabicycloundec-7-ene/Lithium Bromide (DBU/LiBr) - Also Applicable to Cleavage of Peptides from Resins in Merrifield Syntheses
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A mixture of the amidine base 1,8-diazabicycloundec-7-ene (DBU) and LiBr (preferably 0.5 and 5 equiv., resp.) turns out to be a highly efficient catalyst (at 0-25 deg C) for saponifications (in THF/H2O) and transesterifications (in ROH).The scope and limitations of the method are determined using ca. two dozens of different ester/alcohol combinations (Schemes 2 and 3).The investigation is focused on peptides as substrates.Under carefully controlled conditions, no epimerization occurs with N-Boc- and N-Z-protected peptide esters, when methyl, ethyl, isopropyl, or allyl esters are the products, as shown for peptides containing up to six amino acids, with Ala, Leu, MeLeu, Asp(OEt), or Tyr at the C-terminus (Scheme 3 and Tables 1 and 2).Hydrolytic and transesterifying detachments of Boc-Leu-Ala-Gly-Val-OR and Boc-Leu-Ala-Gly-Phe-OR (R = H, Me) from PAM and Wang resins (1-8 h at 0-25 deg C, 2 equiv. of DBU, 5 equiv. of LiBr) can be achieved by this method without epimerization of the C-terminal stereogenic center; a comparison with other methods (HF, Ti(OR)4) is given (Schemes 4 and 5).Possible protecting-group strategies involving the DBU/LiBr method are discussed (Table 3).Extensive experimental details are given.
- Seebach, Dieter,Thaler, Adrian,Blaser, Denis,Ko, Soo Y.
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p. 1102 - 1118
(2007/10/02)
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- tert-Butyloxycarbonyl and Benzyloxycarbonyl Amino Acid Fluorides. New, Stable Rapid-Acting Acylating Agents for Peptide Synthesis
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A new class of rapid-acting acylating agents, α-BOC and Z amino acid fluorides are obtained as stable, often crystalline, compounds by treatment of the protected amino acid cyanuric fluoride.
- Carpino, Louis A.,Mansour, El-Sayed M. E.,Sadat-Aalaee, Dean
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p. 2611 - 2614
(2007/10/02)
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- THE SYNTHESIS OF AMIDES, ESTERS, AND THIOESTERS
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Diethyl 2-(3-oxo-2,3-dihydro-1,2-benzisosulfonazolyl)phosphonate is a highly reactive condensing agent, which provides good yield route to amides, esters, and thioesters from a variety of amines, active hydroxylamines, and thiols and acids.
- Miyake, Muneharu,Kirisawa, Makoto,Tokutake, Norio
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p. 123 - 126
(2007/10/02)
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- ON THE USE OF CARBOXAMIDOMETHYL ESTERS ( CAM ESTERS ) IN THE SYNTHESIS OF MODEL PEPTIDES. SCOPE AND LIMITATIONS
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The usefulness of carboxamidomethyl esters ( CAM esters ) as a carboxyl protecting group for peptide synthesis was demonstrated.The synthesis of the chemotactic peptide For-Met-Leu-Phe-OH as well as the synthesis of Met-enkephalin using CAM ester as carbo
- Martinez, Jean,Laur, Janine,Castro, Bertrand
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p. 739 - 744
(2007/10/02)
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- SYNTHESIS OF 2-ACETAMIDO-1-N--2-DEOXY-β-D-GLUCOPYRANOSYLAMINE AND ANALOGS
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2-Acetamido-1-N--2-deoxy-β-D-glucopyranosylamine and analogs containing D-glucopyranosyl, 4-O-β-D-glucopyranosyl-D-glucopyranosyl, L-Phe-L-Ala, and D-Phe-L-Ser were synth
- Tamura, Masahiro,Okai, Hideo
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p. 207 - 218
(2007/10/02)
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- SEGMENT COUPLING IN PEPTIDE SYTHESIS-II A SIMPLE PREDICTIVE EQUATION CORRELATING RACEMIZATION AND PRIMARY STRUCTURE
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A predictive equation based on extrathermodynamic assumptions is proposed, that allows the prediction of the degree of epimerization in tripeptide model reactions of condensation of peptide segments as a function of the primary structure.The experimental
- Nguyen, Dung Le,Dormoy, Jean-Robert,Castro, Bertrand,Prevot, Daniel
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p. 4229 - 4238
(2007/10/02)
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