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α,β-unsaturated ketones in protic media which involves the transfer of an electron to give aradical anion that rapidly protonates and tautomerizes to give an alkyl radical that is moreeasily reduced than the reagent and is converted into the β,β-diarylalanine [1].The photophysical properties of compounds 2b and 2c were studied in three solvents ofdifferent polarity and compared with those of compounds 1b and 1c (Table 2).Table 2. Maximum absorption (λ abs ) and emission wavelengths (λ em ), molar absorptioncoefficients (ε) and fluorescence quantum yields (Φ F ) for compounds 1b, 1c, 2b and 2cSolventCyclohexaneAcetonitrileEthanolλ abs (nm) (ε/10 4 M -1 cm -1 ) λ em (nm) Φ Fa1b 1c 2b 2c 1b 1c 2b 2c 1b 1c 2b 2c283(3.21)203(6.38)281(3.41)204(6.06)281(3.09)201(6.87)298(1.47)216(7.90)297(1.54)216(8.39)298(1.51)216(8.31)260(3.32)206(6.39)262(3.45)203(6.93)261(3.41)205(6.56)296(0.87)285(1.12)274(0.90)222(8.27)295(0.90)285(1.12)275(0.91)220(8.52)295(0.91)285(1.14)275(0.93)220(8.45)368382368385369387363 318367 318365 3193283393283393273390.067 0.086 0.37 0.130.025 0.044 0.32 0.150.043 0.035 0.40 0.23a Relative to anthracene in ethanol (Φ = 0.27 at 25 ºC) [8] for 1b and 1c; relative tonaphthalene in cyclohexane (Φ F = 0.23 at 25 ºC) [9].The results show that although the dehydroalanines show low quantum yields their reductionproducts show reasonably high fluorescent yields and could be useful as fluorescent markers.AcknowledgmentsFoundation for the Science and Technology (FCT) – Portugal and FEDER (Fundo Europeu de DesenvolvimentoRegional) for support to Centro de Química (CQ-UM) and Centro de Física (CFUM) of U of Minhoand through research project PTDC/QUI/81238/2006, cofinanced by FCT and program FEDER/COMPETE(FCOMP-01-0124-FEDER-007467). G.P. to FCT for a PhD grant SFRH/BD/38766/2007.References1. Grishaw, J., In Electrochem. React. Mechan. Org. Chem. Elsevier, The Netherlands, 2000, p.54-89.2. Ferreira, P.M.T., Monteiro, L.S., In Attanasi, O.A, and Spinelli, D. (Eds.) Targets in HeterocyclicSystems: Chemistry and Properties, Vol. 10, Italian Society of Chemistry, Rome, 2007, p. 152-174.3. a) Zhu, G., Zhang, X. J. Org. Chem. 63, 3133-3138 (1998); b) Ohashi, A., Imamoto, T. Org. Lett. 3,373-375 (2001); c) Shultz, C.S., et al. Org. Lett. 7, 3405-3408 (2005).4. Silva, N.O., et al. Tetrahedron Lett. 44, 3377-3379 (2003).5. Pereira, G., et al. Eur. J. Org. Chem. 464-475 (2010).6. Ferreira, P.M.T., Maia, H.L.S., Monteiro, L.S. Tetrahedron Lett. 44, 2137-2139 (2003).7. a) Zimmer, J.P., et al. Anal. Chem. 43, 1000-1006 (1971); b) Annapoorna, S.R., Prasada, M. J.Electroanal. Chem. 490, 93-97 (2000); c) Quintana-Espinoza, P., et al. Electroanalysis 521-525(2006); d) Pastor, F.T., Drakulic B.J. Tetrahedron Lett. 51, 734-738 (2010).8. a) Melhuish, W.H. J. Phys. Chem. 65, 229-235 (1961); b) Dawson, W.R., Windsor, M. W. J. Phys.Chem. 72, 3251-3260 (1968).9. Berlman, I.B., in Hbk of Fluorescence Spectra of Aromatic Molecules, Academic Press, London, 1971.103
Proceedings of the 31 st European Peptide SymposiumMichal Lebl, Morten Meldal, Knud J. Jensen, Thomas Hoeg-Jensen (Editors)European Peptide Society, 2010New Building Blocks for Solid-Phase Synthesis of PeptideAnalogues: N β -Fmoc-N β -Methyl-aza-β 3 -Amino AcidsKsenija Kisselnova 1,2 , Irène Nicolas 1 , Patrick Bauchat 1 , Jaak Järv 2 ,and Michèle Baudy-Floc’h 11 UMR CNRS 6226, ICMV, University of Rennes 1, Rennes, 35042, France; 2 Institute ofChemistry, University of Tartu, Ravila 14a, Tartu, 50411, EstoniaIntroductionN-Methylation is a precious tool to modify lipophilicity [1], proteolytic stability [2], andbioavailability [3] and to induce conformational rigidity to the peptide backbone [4].However, multiple N-methylation has been seldom employed [5], probably due to theavailability of N-methylated amino acids, as few N-methyl amino acids are commerciallyavailable, and their synthesis is tedious [6].Unnatural aza-β 3 -peptides are synthetic compounds designed to mimic peptides andincrease their bioavailability [7]. They can have chemically diverse side chains, but theyneed to have amide bonds resistant to proteolysis. Yet, additional modifications arerequired to generate peptides with enhanced enzymatic stability and improved oralbioavailability.Results and DiscussionWe have previously reported a method to prepare N β -Fmoc-aza-β 3 -amino acids viareductive amination of glyoxylic acid and Fmoc-hydrazine [8]. Taking into account thisprevious method, we tried to reproduce the same reactions starting from methyl hydrazineR OFmoc NNOHFig. 1. N β -Fmoc-N β -Me-aza-β 3 -aa.instead of hydrazine. Thus the correspondingN-Fmoc-N-Me-hydrazine 2 was prepared using theenhanced nucleophilicity of the methylated N-atomof methylhydrazine 1. Methylhydrazine was treatedat -78°C with fluorenyl chloroformate in thepresence of one equivalent of triethylamine. Themonoacylation occurred on the substituted nitrogenin 92% yield, no acylation was observed on theunsubstituted nitrogen. Then we prepared the N-substituted Fmoc hydrazones bycondensing fluoren-9-yl-methyl carbazate 2 with the appropriate aldehyde or ketone.Reduction of the hydrazone 3 with sodium cyanoborohydride afforded N,N'-trisubstitutedhydrazine 4. From the hydrazine 4 the reductive amination of glyoxylic acid lead to theN β -Fmoc-N β -Methyl-aza-β 3 aa-OH 5 (R = CH 2 R 1 ) (Figure 2 and Table 1).For the monomer glycine a direct reductive amination of glyoxylic acid and fluoren-9-yl-methyl carbazate 2 with NaBH 3 CN and HCl 2N gives the corresponding N β -Fmoc-N β -Methyl aza-β 3 -Gly-OH 5 R=H (Figure 2).Nucleophilic substitution of the corresponding t-butyl bromo acetate with N β -Fmoc-N β -Methyl aza-β 3 -Gly-OH 5 R=H would be an alternative to introduce the side chain forthe aspartic analogue N β -Fmoc-N β -Methyl aza-β 3 -Asp-OH 5 (R=CH 2 CO 2 t-Bu) (Figure 2).MeNHNH 21FmocClNEt 3-78°C92 %FmocNNH 22HOCHCO 2 HR 1 CHOFmoc N R 1 NaBH 3 CN Fmoc N R 1 NaBH 3 CNNN3 HCl 2N4 HCl 2N70-90% 96 %94 %OCHCO 2 HNaBHH3 CN Fmoc NOBrCH 2 CO 2 t-BuHCl 2NN OHDIPEA94 %5 R = H70 %N β -Fmoc-N β -Me-aza-β 3 Gly-OHFmoc NNCO 2 tBuOOHRFmoc NN5 R= CH 2 CO 2 t-BuN β -Fmoc-N β -Me-aza-β 3 Asp-OHOOH5 R= CH 2 R 1N β -Fmoc-N β -Me-aza-β 3 aa-OHFig. 2. Synthesis of N β -Fmoc-N β -Me-aza-β 3 aa 5.104
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Peptides 2010Tales of PeptidesProce
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Peptides 2010Tales of PeptidesProce
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IntroductionWe had the distinct hon
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Scientific programIn planning the 3
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31 st EUROPEAN PEPTIDE SYMPOSIUMSep
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published by John Wiley & Sons as a
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The Josef Rudinger AwardThis award
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Young Investigators' SymposiumThe y
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xxiv
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Design of Peptidyl-Inhibitors for G
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Synthetic Antifreeze Glycopeptide A
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Synthesis and Oxidative Folding of
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Convergent Syntheses of Huprp106-12
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Bactericidal Activity of Small Beta
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Bradykinin Analogues Acylated on Th
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Antimicrobial Activity of Small 3-(
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Interaction of Curcumin with A-Synu
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Fluorescent and Luminescent Fusion
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Cellular Expression of the Human An
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2D IR Spectroscopy of Oligopeptides
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large, non-redundant subset of prot
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The aberrantly glucosylated peptide
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Table 1. Proline cis/trans ratios o
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Table 1. Yields, UV-vis absorption
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Table 1. Purity of the targeted tri
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processes are blocked. Interestingl
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(tb4 n ,1 m )MTII(tb1 n ,4 m )MTIIF
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Fig. 2. a) Part of the 400 MHz HR-M
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Once printed, the amino acid partic
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A) PSA, few seconds73B) PSA, 45 min
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short β strands. In contrast, nume
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neg. control Cs9-Rhd MM-218Fig. 2.
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Table 1. The general structure of t
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% ID in the liver 1 h p.i.100908070
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Peptidyl phosphoranes were first re
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obtained from the same sardines and
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MccJ25 variants were produced by si
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Fig. 2. Proposed signaling mechanis
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Table 1. mCD4-HS12 antiviral activi
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Subject index(S)-2-(1-adamantyl)gly
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chip 18chiral triazine condensing r
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heat stress 348helical conformation
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O-acyl isopeptide method 112obesity
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SH2-ligands 210short collagen-relat
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Author indexAboye, Teshome Leta 142
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Chi, Hongfang 480Chiche, Laurent 6C
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Geronikaki, Athina 444Gessmann, Ren
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Kostova, Kalina 528Kotzia, Georgia
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Nagata, Koji 162Nagayev, Igor Yu. 5
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Salvarese, Nicola 518Sammet, Benedi
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Vauquelin, Georges 138Veiga, Ana Sa
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