- Synthesis of dipeptides from N-hydroxy-3-azaspiro[5,5]undecane-2,4-dione activated α-amino acids
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A simple two step procedure for the synthesis of a dipeptide from N-hydroxy-3-azaspiro[5,5]undecane-2,4-dione (HO-ASUD) activated α-amino acids is described. In presence of DCC, N-hydroxy-3-azaspiro[5,5]undecane-2,4- dione readily esterifies the carboxylic acid group of all the N-protected amino acids to yield crystalline N-hydroxy-3-aza spiro[5,5]undecane-2,4-dione activated carboxy ester. The N-hydroxy-3-aza spiro[5,5]undecane-2,4-dione activated carboxy esters of N-protected amino acids readily condensed with other amino acids and gave a dipeptide. This new method is effective for the DCC coupling of a variety of chiral amino acids without loss of enantiomeric purity. Synthesis of fifteen dipeptides including the hitherto unreported Fmoc-l-Orn(Boc)-Val-OMe, Fmoc-l-Cys(trt)-Gly-OEt and Boc-l-Tyr-Gly-OEt is presented.
- Nowshuddin, Shaik,Ram Reddy
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scheme or table
p. 22 - 25
(2011/04/18)
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- Synthesis of proline-derived dipeptides and their catalytic enantioselective direct aldol reactions: Catalyst, solvent, additive and temperature effects
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A series of dipeptides of l-proline-l-amino acid and l-proline-d-amino acid were synthesized to evaluate the catalytic effect for asymmetric direct aldol reactions. In the direct aldol reaction, a catalyst of l-proline-l-amino acid achieves better enantioselectivity than the corresponding l-proline-d-amino acid catalyst. Solubility of the dipeptide catalysts in the solvents is a key point for achieving a better yield of the direct aldol reaction, while hydrogen bonding of solvent does not play an important role in attaining better enantioselectivity and yield. Yield and enantioselectivity of the direct aldol reaction in water were improved by NMM and SDS additives, but the results that were done in plain DMSO were even better.
- Chen,Sung,Sung, Kuangsen
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experimental part
p. 839 - 845
(2010/08/06)
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- Efficient peptide coupling involving sterically hindered amino acids
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(Chemical Equation Presented) Hindered amino acids have been introduced into peptide chains by coupling N-(Cbz- and Fmoc-α-aminoacyl) benzotriazoles with amino acids, wherein at least one of the components was sterically hindered, to provide compounds 3a-e, (3c +3 c′), 5a-d, (5a + 5a′), 6a-c, (6b + 6b′), 8a-c, 9a-e, 10a-d, and (10a + 10a′) in isolated yields of 41-95% with complete retention of chirality as evidenced by NMR and HPLC analysis. The benzotriazole activation methodology is a new route for the synthesis of sterically hindered peptides. (Note: compound numbers written within brackets represent diastereomeric mixtures or racemates; compound numbers without brackets represent enantiomers.)
- Katritzky, Alan R.,Todadze, Ekaterina,Angrish, Parul,Draghici, Bogdan
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p. 5794 - 5801
(2008/02/09)
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- An Effective Water-Free Aprotic System for Dissolving Free Amino Acids
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An effective water-free system was proposed for dissolution and subsequent use in peptide synthesis of free amino acids and their derivatives. It consists of dimethylformamide, a tertiary base, and inorganic additives. Neutral salts (CF3COONa, Ba(ClO4)2, Ca(ClO4)2, NaClO4, BaI2, or Ca(NO3)2) serve as the inorganic additives that increase the solubility of free amino acids in dimethylformamide and provide true 0.2-3 M amino acid solutions. Triethylamine and N-methylmorpholine are most suitable as the tertiary bases. This system was used in reactions with acylating agents: Boc2O, ZOSu, FmocOSu, and activated derivatives of Nα-protected amino acids or peptides. The corresponding amino acid derivatives or Nα-protected di-, tri-, and tetrapeptides were obtained in yields of 80-99 percent at the reaction times of 30-240 min.
- Raydnov, M. G.,Klimenko, L. V.,Mitin, Yu. V.
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p. 283 - 287
(2007/10/03)
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- Peptides influencing diuresis and natriuresis, a process for their preparation, agents containing them, and their use
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The invention relates to peptides of the formula in which RN denotes an acyl radical, L denotes a radical of a lipophilic, neutral α-amino acid, N denotes a radical of an neutral α-amino acid, B2 denotes the radical of a basic α-amino acid, and RC denotes an amido radical; a process for their preparation, agents containing these peptides, and their use.
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- ARYLOXY AND ARYLACYLOXY METHYL KETONES AS THIOL PROTEASE INHIBITORS
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Thiol protease inhibitors are disclosed having the formula: STR1 or an optical isomer thereof, or a pharmaceutically acceptable salt thereof, wherein:n is 0 or 1;m is 0, 1 or 2;X is H or an N-protecting group; each Y is independently an optionally protected α-amino acid residue;R is an optionally protected α-amino acid side chain that is H or CH 3 or that is bonded to the α-carbon atom to which it is attached by a methylene, methine or phenyl radical; andR' is optionally substituted aryl.
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- Studies of Unusual Amino Acids and Their Peptides. XVII. The Synthesis of Peptides Containing N-Carboxymethyl Amino Acids. II.
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The synthetic routes were investigated to four kinds of tetrapeptides made up of three usual amino acid residues and one N-carboxymethyl (Cm-) amino acid residue.The application of vacuum distillation made the isolation of a Cm-amino acid diester more convenient and efficient compared with the chromatographic methods which had been used previously.The efficiency of peptide bond formation at the imino group of a Cm-amino acid by the acid chloride method was remarkably improved under suitable reaction conditions.In the elongation of the peptide chain from a peptide containing a Cm-amino acid at the C-terminal position, the coupling efficiency was usually poorer than that in the case of the corresponding peptide composed only of the usual amino acid residues, and it depended greatly on the coupling methods, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-1-hydroxybenzotriazole method being generaly the most desirable.
- Miyazawa, Toshifumi,Hiramatsu, Shin'ichi,Tsuboi, Yasuhiro,Yamada, Takashi,Kuwata, Shigeru
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p. 1976 - 1982
(2007/10/02)
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- Bitter Taste of Synthetic C-Terminal Tetrapeptide of Bovine β-Casein, H-Pro196-Val-Leu-Gly-Pro-Arg-Gly-Pro-Phe-Pro-Ile-Ile-Val209-OH, and Its Related Peptides
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The primary structure of bovine β-casein contains the partial sequence of -Pro196-Val-Leu-Gly-Pro-Val-Arg-Gly-Pro-Phe-Pro-Ile-Ile-Val209 in the C-terminal portion.We previously reported that the synthetic C-terminal octapeptide, Arg202-Val209, is extremly bitter with its threshold value 0.004 mM, 250 times as strong as that of caffeine.To further investigate the bitter taste of the C-terminal portion of β-casein, we synthesized the C-terminal tetrapeptide, Pro196-Val209, and some its fragments.A hydrophobic hexapeptide, Pro196-Val201, was twice as bitter as caffein.The bitter taste of decapeptide, Pro200-Val209, was the same as that of Arg202-Val209.Although the tetradecapeptide, Pro196-Val209, was composed of two bitter peptides, Pro196-Val201 and Arg202-Val209, its bitter taste was weaker than that of Arg202-Val209 and its threshold value was 0.015 mM.We suggested that the increase of bitterness in peptides through the introduction of hydrophobic amino acids depended on the number of hydrophobic amino acids added.In addition, the synthetic retro analog of Arg202-Val209 (H-Val-Ile-Ile-Pro-Phe-Pro-Gly-Arg-OH) was not as bitter as Arg202-Val209.This indicated that the sequence of Arg202-Val209 is important for extreme bitterness.
- Shinoda, Ichizo,Fushimi, Akira,Kato, Hironobu,Okai, Hideo,Fukui, Sazuko
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p. 2587 - 2596
(2007/10/02)
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