- Fullerene l -Amino Acids and Peptides: Synthesis under Phase-Transfer Catalysis Using a Phosphine-Borane Linker. Electrochemical Behavior
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A new method to link amino acid and peptide derivatives to [60]fullerene is described. It uses hydrophosphination with a secondary phosphine borane. First, the stereoselective synthesis of secondary phosphine borane amino acid derivatives was achieved by alkylation of phenylphosphine borane with γ-iodo-α-amino ester reagents under phase-transfer catalysis (PTC). Second, a sec-phosphine borane amino ester was saponified and coupled with α, γ-diamino esters to afford the corresponding dipeptide derivatives in good yields. Finally, the hydrophosphination reaction of [60]fullerene by the sec-phosphine borane compounds was performed under PTC to obtain C60-amino acid or dipeptide derivatives in yields up to 80% by P-C bond formation. This addition reaction which proceeds in mild and moderate dilute conditions (0.03 M) leads to [60]fullerene derivatives as epimeric mixtures (~1:1) due to the P-chirogenic center but without racemization of the amino acid or peptide moiety. In addition, the electrochemical behavior of a C60-phosphine borane amino ester was investigated by cyclic voltammetry and spectroelectrochemistry after controlled-potential electrolysis. It showed evidence for the retro-hydrophosphination reaction into free [60]fullerene and sec-phosphine borane amino ester compound. Consequently, the synthesis of sec-phosphine borane amino acids followed by their use in hydrophosphination reactions of [60]fullerene under phase-transfer catalysis has demonstrated a great utility for the preparation of C60-derivatives. Indeed, the hydrophosphination and the retro-hydrophosphination reactions of [60]fullerene/phosphine borane compounds offer a promising new strategy for the reversible immobilization of amino acid or peptide derivatives on carbon nanomaterials such as [60]fullerene.
- Minois, Pauline,Bayardon, Jér?me,Meunier-Prest, Rita,Jugé, Sylvain
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- Peptide Nucleic Acid with Double Face: Homothymine-Homocytosine Bimodal Cα-PNA (bm-Cα-PNA) Forms a Double Duplex of the bm-PNA2:DNA Triplex
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Cα-bimodal peptide nucleic acids (bm-Cα-PNA) are PNAs with two faces and are designed homologues of PNAs in which each aminoethylglycine (aeg) repeating unit in the standard PNA backbone hosts a second nucleobase at Cα through a spacer chain with a triazole linker. Such bm-Cα-PNA with mixed sequences can form double duplexes by simultaneous binding to two complementary DNAs, one to the base sequence on t-amide side and the other to the bases on the Cα side chain. The synthesis of bm-Cα-PNA with homothymine (T7) on the t-amide face and homocytosine (C5) on the Cα side chain through the triazole linker was achieved by solid phase synthesis with the global click reaction. In the presence of complementary DNAs dA8 and dG6 at neutral pH, bm-Cα-PNA 1 forms a higher order pentameric double duplex of a triplex composed of two bm-Cα-PNA-C5:dG5 duplexes built on a core (bm-Cα-PNA-T7)2:dA8 triplex. Circular dichroism studies showed that assembly can be achieved by either triplex first and duplex later or vice versa. Isothermal titration calorimetry data indicated that the assembly is driven by favorable enthalpy. These results validate concurrent multiple complex formation by bimodal PNAs with additional nucleobases at Cα or Cγon the aeg-PNA backbone and open up ways to design programmed supramolecular assemblies.
- Gupta, Manoj Kumar,Madhanagopal, Bharath Raj,Ganesh, Krishna N.
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p. 414 - 428
(2020/12/22)
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- Structural design and synthesis of bimodal PNA that simultaneously binds two complementary DNAs to Form fused double duplexes
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Bimodal PNAs are new PNA constructs designed to bind two different cDNA sequences synchronously to form double duplexes. They are synthesized on solid phase using sequential coupling and click reaction to introduce a second base in each monomer at Cα via alkyltriazole linker. The ternary bimodal PNA:DNA complexes show stability higher than that of individual duplexes. Bimodal PNAs are appropriate to create higher-order fused nucleic acid assemblies.
- Gupta, Manoj Kumar,Madhanagopal, Bharath Raj,Datta, Dhrubajyoti,Ganesh, Krishna N.
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p. 5255 - 5260
(2020/07/16)
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- Design, synthesis, and evaluation, derivatives of the fat-accumulation inhibitor ternatin: Toward ternatin molecular probes
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Ternatin, a cyclic heptapeptide derived from mushroom, strongly inhibits fat accumulation in 3T3-L1 adipocytes. However, its mechanism of action remains unclear. In this Letter, we designed, synthesized, and evaluated its derivatives for use as molecular probes to isolate its target protein. Finally, we successfully established a pair of ternatin molecular probes.
- Kawazoe, Yoshinori,Tanaka, Yoko,Omura, Sachikazu,Uemura, Daisuke
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p. 4445 - 4447
(2014/08/05)
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- Nα-Fmoc-protected ω-azido- and ω-alkynyl-L- amino acids as building blocks for the synthesis of "clickable" peptides
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The growing interest in the 1,4-disubstituted-1,2,3-triazolyl moiety as an amide bond surrogate and its formation through very mild, chemoselective, and bioorthogonal CuI-catalyzed Huisgen 1,3-dipolar [3+2] cycloaddition of an alkynyl to an azi
- Isaad, Alexandra Le Chevalier,Barbetti, Francesca,Rovero, Paolo,D'Ursi, Anna Maria,Chelli, Mario,Chorev, Michael,Papini, Anna Maria
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experimental part
p. 5308 - 5314
(2009/06/18)
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- An efficient procedure for the preparation of 4-substituted 5-aminoimidazoles
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The preparation of O-methylimidates from α-aminonitriles and their subsequent co-cyclization with primary amines to afford 4-substituted 5-aminoimidazoles was studied. It was found that the mildly acidic pyridinium p-toluenesulfonate efficiently catalyzed each stage of the reaction sequence: (a) the formation of the O-methylimidates, (b) their co-cyclization with a variety of primary amines, and (c) certain derivatizations of the resultant heterocycles. The developed reaction conditions tolerate a wide variety of α-aminonitriles and primary amine co-reactants. Thus, it is possible to easily prepare a diverse array of substituted heterocyclic compounds in good yield. The requisite α-aminonitriles were synthesized either from amino acids or by phase-transfer alkylation of a glycine anion equivalent. The unstable free 5-aminoimidazoles were normally protected in situ to provide derivatives (methyl imidates or N,N-dimethylamidines) that were amenable to characterization.
- McLaughlin, Mark,Mohareb, Rafat M.,Rapoport, Henry
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- Amino acid derivatives as HIV aspartyl protease inhibitors
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The present invention relates to a class of amino acid derivatives with HIV aspartyl protease inhibitory properties.
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