- Synthesis of Silacyclic Dipeptides: Peptide Elongation at Both N-And C-Termini of Dipeptide
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A new type of peptide bond formation utilizing silacyclic amino acids or peptides is described. This work has the following advantages: (1) imidazolylsilane is a highly fascinating coupling reagent for dipeptide synthesis from N-,C-Terminal unprotected am
- Hattori, Tomohiro,Yamamoto, Hisashi
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supporting information
p. 1758 - 1765
(2022/02/01)
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- Synthesis of malformin-A1, C, a glycan, and an aglycon analog: Potential scaffolds for targeted cancer therapy
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Improvement in therapeutic efficacy while reducing chemotherapeutic side effects remains a vital objective in synthetic design for cancer treatment. In keeping with the ethos of therapeutic development and inspired by the Warburg effect for augmenting biological activities of the malformin family of cyclic-peptide natural products, specifically anti-tumor activity, a β-glucoside of malformin C has been designed and synthesized utilizing precise glycosylation and solution phase peptide synthesis. We optimized several glycosylation procedures utilizing different donors and acceptors. The overarching goal of this study was to ensure a targeted delivery of a glyco-malformin C analog through the coupling of D-glucose moiety; selective transport via glucose transporters (GLUTs) into tumor cells, followed by hydrolysis in the tumor microenvironment releasing the active malformin C a glycon analog. Furthermore, total synthesis of malformin C was carried out with overall improved strategies avoiding unwanted side reactions thus increasing easier purification. We also report on an improved solid phase peptide synthesis protocol for malformin A1.
- Andreana, Peter R.,Hossain, Farzana,Nishat, Sharmeen
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- Overcoming the Deallylation Problem: Palladium(II)-Catalyzed Chemo-, Regio-, and Stereoselective Allylic Oxidation of Aryl Allyl Ether, Amine, and Amino Acids
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We report herein a Pd(II)/bis-sulfoxide-catalyzed intramolecular allylic C-H acetoxylation of aryl allyl ether, amine, and amino acids with the retention of a labile allyl moiety. Mechanistically, the reaction proceeds through a distinct double-bond isomerization from the allylic to the vinylic position followed by intramolecular carboxypalladation and the β-hydride elimination pathway. For the first time, C-H oxidation of N-allyl-protected amino acids to furnish five-membered heterocycles through 1,3-syn-addition is established with excellent diastereoselectivity.
- Begam, Hasina Mamataj,Jana, Ranjan,Manna, Kartic,Samanta, Krishanu
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supporting information
p. 7443 - 7449
(2020/10/09)
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- A class of quaternary ammonium class chiral ionic liquid and its preparation method
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A quaternary ammonium type chirality ion liquid preparing method belongs to the field of chemical synthesis, characterized in that the synthesis quaternary ammonium type chirality ion liquid has a chirality source from natural amino acid which is rich, environmental friendly, and inexpensive, and the synthesis routes are convenient and environmental friendly and have a low cost. The technical solution of the invention is: using the natural amino acid as a raw material, first esterifying the carboxyl of the amino acid, and then alkylating the amido to obtain quaternary ammonium type chirality ion liquid. The quaternary ammonium chirality ion liquid product is green and environmental friendly, not only has the advantages of less volatile, nonflammability, and iron conductivity and the like as the conventional ion liquid, but also has chirality characteristics such as high chirality splitting and selecting property and chirality inductive effect, thereby hopefully being widely applied in aspects of chirality catalyst, chirality extracting and splitting solvent, spectrum, chromatography, material and other green chemical industries.
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Paragraph 0025; 0026; 0028
(2019/04/06)
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- Asymmetric Synthesis of α-Amino Acids by Organocatalytic Biomimetic Transamination
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A biomimetic enantioselective transamination of α-keto ester derivatives can be realized under mild conditions by using chiral quaternary ammonium arenecarboxylates in the absence of base additives. The corresponding α-amino acids can be used as versatile intermediates for further synthetic transformations that furnish chiral pyrrolidine and octahydroindolizine derivatives.
- Kang, Qi-Kai,Selvakumar, Sermadurai,Maruoka, Keiji
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supporting information
p. 2294 - 2297
(2019/04/10)
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- A mild, copper-catalysed amide deprotection strategy: Use of tert-butyl as a protecting group
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Mild methods for the deprotection of organic substrates are of fundamental importance in synthetic chemistry. A new room temperature method using a catalytic amount of Cu(OTf)2is reported. This allows use of the tert-butyl group as an amide protecting group. The methodology is also extended to Boc-deprotection.
- Evans, Vikki,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 7593 - 7597
(2014/12/10)
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- Asymmetric α-2-tosylethenylation of N,N-dialkyl-l-amino acid esters via the formation of non-racemic ammonium enolates
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Asymmetric α-2-tosylethenylation of (S)-2-(pyrrolidin-1-yl)propanoic acid esters was shown to produce good yields with high enantioselectivities. The reaction proceeds via the formation of a non-racemic ammonium enolate without an external source of chirality.
- Tayama, Eiji,Igarashi, Tomohito,Iwamoto, Hajime,Hasegawa, Eietsu
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p. 339 - 345
(2012/01/19)
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- Synthesis of analogues of ochratoxin A
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Four analogues of ochratoxin A (OTA) differing for the aminoacidic moiety were synthesised using ochratoxin (OTα) as the starting material. The condensation reaction between protected amino acids and OT, carried out in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC?HCl) and N-hydroxybenzotriazole (HOBt) as coupling agents, followed by deprotection and PTLC purification afforded OTA alanine, leucine, serine and tryptophane analogues in satisfactory yields (33-47%, based on OT).
- Plastina, Pierluigi,Fazio, Alessia,Attya, Mohamed,Sindona, Giovanni,Gabriele, Bartolo
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p. 1799 - 1805
(2020/03/18)
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- Structural optimization of azadipeptide nitriles strongly increases association rates and allows the development of selective cathepsin inhibitors
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Using the example of cathepsin K, we demonstrate the design of highly potent and selective azadipeptide nitrile inhibitors. A systematic scan with respect to P2 and P3 substituents was carried out. Structural modifications strongly affected the enzyme-inh
- Frizler, Maxim,Lohr, Friederike,Furtmann, Norbert,Kl?s, Julia,Gütschow, Michael
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supporting information; experimental part
p. 396 - 400
(2011/03/18)
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- Pyrrolinone-pyrrolidine oligomers as universal peptidomimetics
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Peptidomimetics 1-3 were prepared from amino acid-derived tetramic acids 7 as the key starting materials. Calculations show that preferred conformations of 1 can align their side-chain vectors with amino acids in common secondary structures more effectively than conformations of 3. A good fit was found for a preferred conformation of 2 (an extended derivative of 1) with a sheet/β-turn/sheet motif.
- Raghuraman, Arjun,Ko, Eunhwa,Perez, Lisa M.,Ioerger, Thomas R.,Burgess, Kevin
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supporting information; experimental part
p. 12350 - 12353
(2011/10/02)
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- (9H-fluoren-9-yl)methanesuIfonyl (Fms): An amino protecting group complementary to Fmoc
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A sulfonamide-based protecting group (PG), (9H-fluoren-9yl)methanesulfonyl (Fms), which can be used in a similar way to the well-established Fmoc PG, was developed. The advantages of this new PG were demonstrated in the successful formation of a phosphonamide between an N-Fmsprotected a-phosphonoalanine monoester and secondary alkylamines, including (R)-2-phenylethylamine, (S)-phenylalanine iert-butyl ester (H-Phe-OtBu), H-Pro-Gly-OtBu, and H-Phe-Phe-OtBu, without formation of oxazaphospholine, which is a serious problem associated with the Fmoc PG. The success should pave the way to the solid-phase synthesis of unnatural peptides substituted with a-amino phosphonic acid (AP) at essentially any arbitrary position without significant modification of the Fmoc-based chemistry that has been accumulated since Carpino's report in 1970. The N-Fms-AP monomer would attract much attention in the field of peptide mimetics.
- Ishibashi, Yoshitaka,Miyata, Kengo,Kitamura, Masato
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experimental part
p. 4201 - 4204
(2010/10/02)
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- Activity-based proteome profiling of potential cellular targets of orlistat - An FDA-approved drug with anti-tumor activities
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Orlistat, or tetrahydrolipstatin (THL), is an FDA-approved antiobesity drug with potential antitumor activities. Cellular off-targets and potential side effects of Orlistat in cancer therapies, however, have not been extensively explored thus far. In this study, we report the total of synthesis of THL-like protein-reactive probes, in which extremely conservative modifications (i.e., an alkyne handle) were introduced in the parental THL structure to maintain the native biological properties of Orlistat, while providing the necessary functionality for target identification via the bio-orthogonal click chemistry. With these natural productlike, cell-permeable probes, we were able to demonstrate, for the first time, this chemical proteomic approach is suitable for the identification of previously unknown cellular targets of Orlistat. In addition to the expected fatty acid synthase (FAS), we identified a total of eight new targets, some of which were further validated by experiments including Western blotting, recombinant protein expression, and site-directed mutagenesis. Our findings have important implications in the consideration of Orlistat as a potential anticancer drug at its early stages of development for cancer therapy. Our strategy should be broadly useful for off-target identification against quite a number of existing drugs and/or candidates, which are also covalent modifiers of their biological targets.
- Yang, Peng-Yu,Liu, Kai,Ngai, Mun Hong,Lear, Martin J.,Wenk, Markus R.,Yao, Shao Q.
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supporting information; experimental part
p. 656 - 666
(2010/03/25)
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- Addition of allylzinc to a-amino acid-derived imines: Synthesis of diamino alcohols by Hydroboration
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Imines obtained by condensation of Z-pro- tected or Boc-protected α-amino aldehydes with α-amino tert-butyl esters or with O-silyl-protected amino alcohols were reacted with preformed allyl zinc yielding homoal- lylamines with yields around 50% and selectivities ranging from 50:50 to 90:10. Hydroboration of the terminal double bond furnished diamino alcohols with yields up to 97%. The configuration of the substrates was determined by X-ray-crystallographic analysis of a hydroboration product and comparison of physical data. Springer-Verlag 2010.
- Virlouvet, Mickael,Goesmann, Helmut,Feldmann, Claus,Podlech, Joachim
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experimental part
p. 177 - 198
(2010/08/05)
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- The (2-phenyl-2-trimethylsilyl)ethoxycarbonyl (Psoc) group - A novel amino protecting group
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A novel silicon containing protecting group has been developed based on the known 2-(trimethylsilyl)ethyl system. The new protecting group is cleaved under very mild conditions by treatment with tetra-n-butylammonium fluoride in CH2Cl2 much more rapidly than the 2-(trimethylsilyl)ethoxycarbonyl group, leading to less side reactions.
- Wagner,Heiner,Kunz
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p. 1753 - 1756
(2007/10/03)
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