- Synthesis of N-Benzyloxycarbonyl-N-methylaminoacids from Oxazolidine-5-one Derivatives
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Hydrogenolysis of 3-benzyloxycarbonyloxazolidine-5-one and 3-benzyloxycarbonyl-4-benzyloxazolidine-5-one by Et3SiH in the presence of F3CCO2H is demonstrated to be a convenient method for preparing substituted N-methylaminoacids.In contrast with catalytic
- Chipens, G. I.,Slavinskaya, V. A.,Sile, D. E.,Korchagova, E. Kh.,Katkevich, M. Yu.,Grigor'eva, V. D.
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- Design, synthesis, and optimization of balanced dual NK1/NK 3 receptor antagonists
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In connection with a program directed at potent and balanced dual NK 1/NK3 receptor ligands, a focused exploration of an original class of peptidomimetic derivatives was performed. The rational design and molecular hybridization of a novel phenylalanine core series was achieved to maximize the in vitro affinity and antagonism at both human NK1 and NK3 receptors. This study led to the identification of a new potent dual NK1/NK3 antagonist with pKi values of 8.6 and 8.1, respectively.
- Hanessian, Stephen,Jennequin, Thomas,Boyer, Nicolas,Babonneau, Vincent,Soma, Udaykumar,Mannoury La Cour, Clotilde,Millan, Mark J.,De Nanteuil, Guillaume
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supporting information
p. 550 - 555
(2014/06/09)
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- Enantioselective direct α-amination of aldehydes via a photoredox mechanism: A strategy for asymmetric amine fragment coupling
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The direct, asymmetric α-amination of aldehydes has been accomplished via a combination of photoredox and organocatalysis. Photon-generated N-centered radicals undergo enantioselective α-addition to catalytically formed chiral enamines to directly produce stable α-amino aldehyde adducts bearing synthetically useful amine substitution patterns. Incorporation of a photolabile group on the amine precursor obviates the need to employ a photoredox catalyst in this transformation. Importantly, this photoinduced transformation allows direct and enantioselective access to α-amino aldehyde products that do not require postreaction manipulation.
- Cecere, Giuseppe,Koenig, Christian M.,Alleva, Jennifer L.,MacMillan, David W. C.
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p. 11521 - 11524
(2013/09/02)
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- Synthesis of N-methyl L-phenylalanine for total synthesis of pepticinnamin e
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The target compounds 3, 10 and 11 were synthesized through different N-methylation strategies. The concise and efficient preparation of them in large scale was developed and 3, 10 and 11 were obtained in suitable form used for both nitrogen-end and oxygen-end extension in next coupling reaction in peptides synthesis, specifically in total synthesis of natural pepticinnamin E.
- Sun, Dequn,Zhang, Lingzi,Wang, Jin
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experimental part
p. 319 - 322
(2012/09/07)
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- Total synthesis and biological evaluation of tamandarin B analogues
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(Chemical Equation Presented) Tamandarins A and B are a class of marine natural cyclodepsipeptides with structures and biological activities closely related to those of the didemnins. The easier synthetic access to tamandarins accelerates the preparation of new macrocyclic derivatives of this family of antitumor, antiviral, and immunosuppressive compounds. The optimization of the previously reported synthetic route to tamandarins by changing the macrolactamization site from Nst1 and Thr6 to Pro 4 and N,O-Me2Tyr5 residues led to a significant improvement in the reaction yield. Using this new synthetic approach, four new macrocyclic analogues of tamandarin B were prepared and evaluated for anticancer activity. These results provide further insight into the structure-activity relationship of the tamandarins and didemnins.
- Adrio, Javier,Cuevas, Carmen,Manzanares, Ignacio,Joullie, Madeleine M.
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p. 5129 - 5138
(2008/02/07)
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- Total synthesis of ulongamide A, a cyclic depsipeptide isolated from marine cyanobacteria Lyngbya sp.
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A total synthesis of ulongamide A (1), a cytotoxic natural cyclic depsipeptide, was achieved by a convergent route involving coupling of the fragments 7 and 8 to the pentapeptide 24, and subsequent cyclization thereof after prior removal of the t-Boc protecting groups.
- Alvarado, Cuauhtémoc,Díaz, Eduardo,Guzmán, ángel
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p. 603 - 607
(2007/10/03)
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- 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 and biological evaluation of tamandarin B analogues
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The synthesis of two tamandarin B analogues in which the N,O-Me 2Tyr5 unit was replaced by N-Me-phenylalanine (N-MePhe5) and (S)-2-(methylamino)-3-(naphthalen-2-yl)propanoic acid (N-MeNaphth5) is described. The
- Adrio, Javier,Cuevas, Carmen,Manzanares, Ignacio,Joullie, Madeleine M.
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p. 511 - 514
(2007/10/03)
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- Synthesis of the marine natural product barbamide
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The first total synthesis of the trichlorinated natural product barbamide is described. The convergent approach involves coupling (S)-3-trichloromethylbutanoyl chloride with Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) to give 15 followed by additi
- Nguyen,Willis,Gerwick
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p. 1934 - 1935
(2007/10/03)
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- The Dakin-West reaction of N-alkoxycarbonyl-N-alkyl-α-amino acids employing trifluoroacetic anhydride
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The Dakin-West reaction of N-alkoxycarbonyl-N-alkyl-α-amino acids (1a - j) with trifluoroacetic anhydride in the presence of pyridine gave α-amido trifluoromethyl ketones (2a - j), in which probable intermediates were mesoionic 1,3-oxazolium-5-olates (munchnones). The diastereoselective reduction of 2a - f with NaBH4 gave the threo-aminoalcohols (5a - f), which may be explained by the Felkin-Anh model. This was confirmed by converting 5a - f into trans-5-trifluoromethyl-2-oxazolidinones (6a - f) in good yields.
- Kawase, Masami,Hirabayashi, Michitaka,Kumakura, Hiroko,Saito, Setsuo,Yamamoto, Katsumi
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p. 114 - 119
(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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- Synthesis and biological activities of [N-MeLeu5]- and [N-MePhe5]- didemnin B
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Based on information from X-ray, NMR, and SAR data, the N,O-diMeTyr5 unit of didemnin B was believed to be important for biological activity. To determine the importance of aromaticity and the role of the methoxy group in this unit, two analogs
- Pfizenmayer, Amy J.,Ramanjulu, Joshi M.,Vera, Matthew D.,Ding, Xiaobin,Xiao, Dong,Chen, Wei-Chuan,Joullie, Madeleine M.
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p. 313 - 334
(2007/10/03)
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- The effects of N-methylation on the enantioselectivity of catalysis by cyclo[(R)-His-(R)-Phe]
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The cyclic dipeptide cyclo[(R)-His-(R)-Phe] 1 has been known since 1981 to catalyze the enantioselective formation of cyanohydrins from aldehydes and HCN. Although 1 has proved to be very effective in the production of optically active cyanohydrins, the p
- Thoen, Jason C.,Lipton, Mark A.
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p. 3947 - 3954
(2007/10/03)
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- Development of Potent and Selective CCK-A Receptor Agonists from Boc-CCK-4: Tetrapeptides Containing Lys(Nε)-Amide Residues
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A series of Boc-CCK-4 derivatives represented by the general structure Boc-Trp-Lys(Nε-COR)-Asp-Phe-NH2, where R is an aromatic, heterocyclic, or aliphatic group, are potent and selective CCK-A receptor agonists.These amide-bearing compounds complement the previously described urea-based tetrapeptides (Shiosaki et al.J.Med.Chem. 1991,34,2837-2842); structure-activity studies revealed parallel as well as divergent trends between these two series.A significant correlation was observed between pancreatic binding affinity and the resonance constant R of the phenyl substituent in one particular series of derivatives.Sulfation of phenolic amides appended onto the ε-amino group of the lysine did not affect affinity for the CCK-A receptor in contrast to the 500-fold increase in binding potency observed upon sulfation of CCK-8, suggesting that the lysine appendage and the sulfated tyrosine in CCK-8, both key structural elements that impart high affinity for the CCK-A receptor, are interacting differently with the receptor.The amide-bearing tetrapeptides are full agonists relative to CCK-8 in stimulating pancreatic amylase release while being partial agonists in eliciting phosphoinositide (PI) hydrolysis.Both effects were blocked by selective CCK-A receptor antagonists
- Shiosaki, Kazumi,Lin, Chun Wel,Kopecka, Hana,Craig, Richard A.,Bianchi, Bruce R.,et al.
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p. 2007 - 2014
(2007/10/02)
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- THE SYNTHESIS OF A Nγ-PHTHALYL-Nα-METHYL-α,γ-DIAMINOBUTYRYL CONGENER OF VIRGINIAMYCIN S1
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A synthesis of (A2bu=α,γ-diaminobutyric acid) is reported using the very efficient coupling agent BOP-Cl (N,N'-bis(3-oxo-2-oxazolidinyl)phosphinic chloride) for imino acid peptide bond formation.The total yield is 11percent for the 5 coupling steps and one lactonization.The final step was a cyclization between residues 5 and 6, after (I) first t-Boc acidic deprotection with 85percent HCOOH of the linear precursor Z-Thr(Nα-Boc-Phg-O-)-D-Abu-Pro-MePhe-MeA2bu(γPht)-OBut followed by (ii) acidic saponification (Tfa) of the t-Bu ester.This sequence was found to be prerequisite, in view of the extreme lability of the 4-5 peptide bond under acidic conditions.
- Anteunis, M. J. O.,Auwera, C. Van der,Vanfleteren, L.,Borremans, F.
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p. 135 - 148
(2007/10/02)
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