- Effective methods for the synthesis of N-methyl β-amino acids from all twenty common α-amino acids using 1,3-oxazolidin-5-ones and 1,3-oxazinan-6-ones
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N-Methyl β-amino acids are generally required for application in the synthesis of potentially bioactive modified peptides and other oligomers. Previous work highlighted the reductive cleavage of 1,3-oxazolidin-5-ones to synthesise N-methyl α-amino acids. Starting from α-amino acids, two approaches were used to prepare the corresponding N-methyl β-amino acids. First, α-amino acids were converted to N-methyl α-amino acids by the so-called '1,3-oxazolidin-5-one strategy', and these were then homologated by the Arndt-Eistert procedure to afford N-protected N-methyl β-amino acids derived from the 20 common α-amino acids. These compounds were prepared in yields of 23-57% (relative to N-methyl α-amino acid). In a second approach, twelve N-protected α-amino acids could be directly homologated by the Arndt-Eistert procedure, and the resulting β-amino acids were converted to the 1,3-oxazinan-6-ones in 30-45% yield. Finally, reductive cleavage afforded the desired N-methyl β-amino acids in 41-63% yield. One sterically congested β-amino acid, 3-methyl-3-aminobutanoic acid, did give a high yield (95%) of the 1,3-oxazinan-6-one (65), and subsequent reductive cleavage gave the corresponding AIBN-derived N-methyl β-amino acid 61 in 71% yield (Scheme 2). Thus, our protocols allow the ready preparation of all N-methyl β-amino acids derived from the 20 proteinogenic α-amino acids.
- Hughes, Andrew B.,Sleebs, Brad E.
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p. 2611 - 2637
(2007/10/03)
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- Synthesis of new β-amino acids via 5-oxazolidinones and the arndt-eistert procedure
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N-Methyl β-amino acids are potentially useful amino acid derivatives for incorporation in lead peptide therapeutics. The syntheses of five such compounds are presented. Their synthesis via 6-oxazinanones was low yielding. Alternatively, reductive cleavage of a 5-oxazolidinone gave the N-methyl β-amino acid, which was then homologated via an Arndt-Eistert procedure in high yield to give the N-methyl α-amino acid. CSIRO 2005.
- Hughes, Andrew B.,Sleebs, Brad E.
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p. 778 - 784
(2007/10/03)
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- Stereocontrolled synthesis of onchidins
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(Chemical Equation Presented) The first total synthesis of a molecule possessing the stereochemistry proposed for onchidin is described. The structure synthesized appears to be different from that of the marine natural product.
- Peng, Yungui,Pang, Heung Wing,Ye, Tao
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p. 3781 - 3784
(2007/10/03)
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- Synthesis and anti-Helicobacter pylori activity of pyloricidin derivatives. I. Structure-activity relationships on the terminal peptidic moiety
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The novel natural antibiotics pyloricidin A, B and C possess potent and highly selective antibacterial activity against Helicobacter pylori. In order to investigate the structure activity relationships for the terminal peptidic moiety, a series of pyloricidin B and pyloricidin C derivatives, bearing various amino acids in the moiety, were prepared and evaluated for their anti-H. pylori activity. The derivatives bearing α-D-, β- and γ-amino acids or peptidemimetics showed drastically decreased activity. On the other hand, the derivatives with α-L-amino acids were found to maintain the activity. Among the derivatives prepared in this work, the allyglycine derivative 2s showed the most potent anti-H. pylori activity, with an MIC value of less than 0.006 μg/ml against H. pylori NCTC11637, which is 60-fold greater than the activity of the lead compound pyloricidin C.
- Hasuoka, Atsushi,Nishikimi, Yuji,Nakayama, Yutaka,Kamiyama, Keiji,Nakao, Masafumi,Miyagawa, Ken-Ichiro,Nishimura, Osamu,Fujino, Masahiko
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p. 322 - 336
(2007/10/03)
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- A simple and rapid protocol for N-methyl-α-amino acids
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A two step strategy for optically pure N-Protected-N-methyl-α-amino acids starting from N-protected-α-amino acids via reductive cleavage of oxazolidinones using NaCNBH3/TMSCl is described.
- Reddy, G. Vidyasagar,Iyengar
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p. 299 - 300
(2007/10/03)
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- Inhibition of human leukocyte elastase (HLE) by N-substituted peptidyl trifluoromethyl ketones
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A series of tripeptides possessing trifluoromethyl or aryl ketone residues at P1 were prepared and evaluated both in vitro and in vivo as potential inhibitors of human leukocyte elastase (HLE). Tripeptides containing non naturally occurring N-substituted glycine residues at the P2-position have been demonstrated to be potent in vitro inhibitors of HLE, with IC50 values in the submicromolar range. Sterically demanding substituents on the P2- nitrogen have no detrimental effect on in vitro potency. The inhibition process presumably acts via hemiketal formation with the active site Ser195 of HLE, and is facilitated by the strongly electron withdrawing trifluoromethyl functionality. Deletion of the amino acid at the P3-subsite region affords inactive compounds. Valine is the preferred residue at the P1-position, whereas the corresponding glycine, alanine, α,α- dimethylglycine, or phenylalanine analogues are all inactive. The compounds described herein all confer a high degree of in vitro specificity when tested against representative cysteine, aspartyl, metallo, and other serine proteases. One of the most potent in vitro inhibitors is (3RS)-N-[4[[[(4- chlorophenyl)sulfonyl]amino]carbonyl]phenyl]oxomethyl]-L-valyl-N-(2,3- dihydro-1H-inden-2-yl)glycine N-[3-(1,1,1-trifluoro-4-methyl-2- oxopentyl)amide (20i; BI-RA-260) (IC50 = 0.084 μM). Compound 20i was also tested in hamsters in an elastase-induced pulmonary hemorrhage (EPH) model. In this model, intratracheal (it.) administration of 20i, 5 min prior to HLE challenge, effectively inhibited hemorrhage in a dose-dependent manner with an ED50 of 4.8 μg. The inhibitor 20i, 20 μg administered it. 24, 48, and 72 h prior to HLE challenge, exhibits significant inhibition against hemorrhage at all time points (97%, 64% and 49%, respectively). In a 21-day chronic model of emphysema in hamsters, 200 μg of HLE administered it. caused an elastase-induced emphysema in the lungs which can be quantitated histologically utilizing image analysis. In this assay, 20i significantly inhibited pulmonary lesions associated with septal destruction and increased alveolar spaces, when dosed at 20 μg it. 5 min prior to challenge with HLE.
- Skiles,Fuchs,Miao,Sorcek,Grozinger,Mauldin,Vitous,Mui,Jacober,Chow,Matteo,Skoog,Weldon,Possanza,Keirns,Letts,Rosenthal
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p. 641 - 662
(2007/10/02)
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- Acyl derivatives
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Peptide derivatives provided by the present invention are compounds of the general formula STR1 wherein R1 represents a hydrogen atom or the methyl or hydroxymethyl group or a mono-, di- or trihalomethyl mgroup; R2 represents the cha
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